DIY- How to Maintain the CLIMATE CONTROL SYSTEM
01-24-2011, 09:45 PM
#1
Burning Brakes
Thread Starter
DIY- How to Maintain the CLIMATE CONTROL SYSTEM
There are two simple things that you can do to maintain and help prevent problems with the Climate Control HVAC (Heating, Ventilation, and Air Conditioning) System in your Acura RDX:
Ø Run the air conditioner for 10 minutes every week or so during the winter, and
Ø Run the heater for 5 minutes every week or so during the summer.
WHY RUN THE AC (AIR CONDITIONER) IN THE WINTER?
Running the AC (air conditioner compressor) unit for 10 minutes during the winter will allow the Freon (refrigerant gas) and lubricating oils to circulate in the car’s system. This will prevent the rubber seals/ O-rings from drying and allowing the Freon to escape. Once a seal has allowed Freon to escape, probably a Freon recharge will not re-condition the seal enough that it does not have to be replaced. And the oil will also help prevent any corrosion of the interior metal parts, such as the condenser/ evaporator.
The 1994 Accord Owner’s Manual contained a short statement, suggesting that the AC unit be run regularly during the winter. I do not have a copy handy, so I cannot tell you how often or for how long you were supposed to do this. Back in the dark ages of the 1950s and 1960s, everyone knew to do this. Most people did not have ACs in their cars because they were very expensive system options. So if you had one, you did everything to make it last.
OK, so you are probably thinking how much can it cost to just replace a few line seals and recharge the system? If a seal fails, it will require one or more hours to find it and then fix it, at a cost of more than $100 per hour (labor rate).
And if the front seal on the AC compressor fails, you will get a new or rebuilt compressor. This is the seal around the main shaft with the drive pulley on it. No, the shaft does not turn all of the time when the engine is running, only the pulley does. The shaft (and compressor) turns only when the clutch is engaged.
A mechanic repairs your car, by replacing parts. A mechanic does not repair individual parts. Not only is the AC compressor seal not available from the dealer/ Acura, but neither is the AC compressor motor as an individual part. A complete unit must be purchased, including the Compressor Motor, Coil Set, Pulley and Clutch, Wire sub-Harness, etc. at a current cost of $500 plus labor to install.
And if the compressor actually fails (mechanically) because the Freon leaked out, and it destroyed itself internally because there was no oil (no Freon no oil), it will have distributed metal and other swarf throughout the entire AC system. Do a web search for ‘Accord Black Death’, or ‘Chevy Black Death’, or ‘Ford Black Death’, etc. The problem is not with Honda or any particular company, the problem is with rotary rather than the old style pump compressors. The old style compressors were much less likely to destroy the rest of the AC system when they failed (evaporator, condenser, lines, etc.). But they were twice the size and weight.
Repair (joke) or replacement of other parts of the HVAC system, required when an AC compressor fails mechanically, currently average over $1500 total (including the compressor).
HOW TO RUN THE AC IN THE WINTER
Wait, don’t I just push the AC button, and let it run for 10 minutes? No, because if the outside temperature is less than 40 degrees F, then the AC is not going to run, period. And the outside air temperature sensor does not read accurately when the vehicle speed is below 19 mph. The outside temperature is displayed on the MID (multi-information display) located in the dash, behind the steering wheel.
I thought that perhaps I could pull into the heated receiving bay of my local dealer, and get the AC to run while parked inside the building. But the temp sensor just kept reading the outside temp of 27 degrees. Perhaps if I had let the car sit inside for awhile, the MID temp would have updated. So for now I can only suggest that you watch out for one of those rare warm winter days. And if you actually find another way that works, please let the rest of us know about it – thanks.
Ø When the outside temperature is above 40 degrees, drive the car until the engine reaches normal temperature. Use this time to also heat the interior as warm as possible. Then when the AC is run, you will not be so uncomfortable.
Ø To force the AC to run at a low outside temperature, you will likely need to set the HVAC system temperature ‘request’ to ‘Lo’. Read the Owner’s Manual, but this means lowering the temperature request to the lowest setting. This forces the HVAC system into a manual mode, versus the normal automatic mode.
Ø Press the AC button, and check that the A/C ON lettering is displayed on the temperature control display in the center of the dash. Then set the fan switch to the lowest setting.
Ø Now set the temperature request level back up to around 70 degrees. The AC should continue to run, as well as the heater.
Ø Wait 10 minutes and done. And park the car while you fiddle around with this, then drive as you want. Safety first.
The AC compressor is not going to run constantly anyway. That is why the HVAC system should be asked to run the AC for 10 minutes. The HVAC control computer is going to be reading the interior temp sensor, and will understand that you are asking the AC to cool an interior that is already cool. It will not comply – in other words, the AC compressor will only run for a few seconds at a time, cycling ON and OFF.
A last suggestion: run the AC on maximum every couple of weeks even in the summer. Why? Because most of the time, even in the summer, the AC system is only sort of loafing along. It needs to be run at max every so often, to maximize flow of the Freon and more importantly the oil, throughout the entire system. Of course, this depends upon where you live. For those in Vegas, probably every time you enter the car, the AC gets a full workout.
WHY RUN THE HEATER IN THE SUMMER?
The idea is to maximize the anti-corrosion ability of the anti-freeze, to prevent internal corrosion of the heater core from causing a pin-hole leak. This works best when the coolant is flowed/ flushed over the inner heater core surfaces, scouring away any minor corrosion or accumulated sediment (to prevent clogging the core). It is simply not good for the heater core to sit with stagnant coolant for 6 months.
The RDX heater core has a valve inside the inlet coolant line. Unless the heater is run at maximum, this valve is always either partly or completely closed. This limits (or prevents entirely) coolant flow through the heater core.
Although a new RDX heater core is probably only about $100, the labor to replace it is probably about 15 hours. The first step in replacing the RDX heater core, is to evacuate (remove) the Freon from the AC system, then disconnect the lines to the AC evaporator inside the car. The evaporator is sitting under the dash, just next to the heater core. Next step is to remove the dash: loosen the steering wheel shaft, disconnect all of the air bag electricals, etc. Well, I guess you get the idea.
HOW TO RUN THE HEATER IN THE SUMMER
In order to maximize the coolant flow through the heater core, the inlet hose valve must be forced completely open. The only way to do this is to set the HVAC temperature request to ‘Hi’. This places the HVAC system in manual mode. Check the Owner’s Manual. Set the fan control to minimum. I do not know if the RDX AC can be run at the same time (while the heater is on). My Chevy Blazer does allow this ‘dual’ model, which is how I do it for the Blazer.
As a suggestion, first warm the engine to normal operating temperature, and also use the AC system to cool the interior. That will limit the discomfort of running the heater when it is 100 degrees outside (or wait for a cooler day or night). It is probably not necessary to run the heater for more than a couple of minutes, and certainly not more than 5 minutes, during the summer.
But consider running the heater on HI during the winter, every so often. That will ensure maximum coolant flow through the heater core, and maximum corrosion protection, during the winter months.
CHEERS.
-----eof
Ø Run the air conditioner for 10 minutes every week or so during the winter, and
Ø Run the heater for 5 minutes every week or so during the summer.
WHY RUN THE AC (AIR CONDITIONER) IN THE WINTER?
Running the AC (air conditioner compressor) unit for 10 minutes during the winter will allow the Freon (refrigerant gas) and lubricating oils to circulate in the car’s system. This will prevent the rubber seals/ O-rings from drying and allowing the Freon to escape. Once a seal has allowed Freon to escape, probably a Freon recharge will not re-condition the seal enough that it does not have to be replaced. And the oil will also help prevent any corrosion of the interior metal parts, such as the condenser/ evaporator.
The 1994 Accord Owner’s Manual contained a short statement, suggesting that the AC unit be run regularly during the winter. I do not have a copy handy, so I cannot tell you how often or for how long you were supposed to do this. Back in the dark ages of the 1950s and 1960s, everyone knew to do this. Most people did not have ACs in their cars because they were very expensive system options. So if you had one, you did everything to make it last.
OK, so you are probably thinking how much can it cost to just replace a few line seals and recharge the system? If a seal fails, it will require one or more hours to find it and then fix it, at a cost of more than $100 per hour (labor rate).
And if the front seal on the AC compressor fails, you will get a new or rebuilt compressor. This is the seal around the main shaft with the drive pulley on it. No, the shaft does not turn all of the time when the engine is running, only the pulley does. The shaft (and compressor) turns only when the clutch is engaged.
A mechanic repairs your car, by replacing parts. A mechanic does not repair individual parts. Not only is the AC compressor seal not available from the dealer/ Acura, but neither is the AC compressor motor as an individual part. A complete unit must be purchased, including the Compressor Motor, Coil Set, Pulley and Clutch, Wire sub-Harness, etc. at a current cost of $500 plus labor to install.
And if the compressor actually fails (mechanically) because the Freon leaked out, and it destroyed itself internally because there was no oil (no Freon no oil), it will have distributed metal and other swarf throughout the entire AC system. Do a web search for ‘Accord Black Death’, or ‘Chevy Black Death’, or ‘Ford Black Death’, etc. The problem is not with Honda or any particular company, the problem is with rotary rather than the old style pump compressors. The old style compressors were much less likely to destroy the rest of the AC system when they failed (evaporator, condenser, lines, etc.). But they were twice the size and weight.
Repair (joke) or replacement of other parts of the HVAC system, required when an AC compressor fails mechanically, currently average over $1500 total (including the compressor).
HOW TO RUN THE AC IN THE WINTER
Wait, don’t I just push the AC button, and let it run for 10 minutes? No, because if the outside temperature is less than 40 degrees F, then the AC is not going to run, period. And the outside air temperature sensor does not read accurately when the vehicle speed is below 19 mph. The outside temperature is displayed on the MID (multi-information display) located in the dash, behind the steering wheel.
I thought that perhaps I could pull into the heated receiving bay of my local dealer, and get the AC to run while parked inside the building. But the temp sensor just kept reading the outside temp of 27 degrees. Perhaps if I had let the car sit inside for awhile, the MID temp would have updated. So for now I can only suggest that you watch out for one of those rare warm winter days. And if you actually find another way that works, please let the rest of us know about it – thanks.
Ø When the outside temperature is above 40 degrees, drive the car until the engine reaches normal temperature. Use this time to also heat the interior as warm as possible. Then when the AC is run, you will not be so uncomfortable.
Ø To force the AC to run at a low outside temperature, you will likely need to set the HVAC system temperature ‘request’ to ‘Lo’. Read the Owner’s Manual, but this means lowering the temperature request to the lowest setting. This forces the HVAC system into a manual mode, versus the normal automatic mode.
Ø Press the AC button, and check that the A/C ON lettering is displayed on the temperature control display in the center of the dash. Then set the fan switch to the lowest setting.
Ø Now set the temperature request level back up to around 70 degrees. The AC should continue to run, as well as the heater.
Ø Wait 10 minutes and done. And park the car while you fiddle around with this, then drive as you want. Safety first.
The AC compressor is not going to run constantly anyway. That is why the HVAC system should be asked to run the AC for 10 minutes. The HVAC control computer is going to be reading the interior temp sensor, and will understand that you are asking the AC to cool an interior that is already cool. It will not comply – in other words, the AC compressor will only run for a few seconds at a time, cycling ON and OFF.
A last suggestion: run the AC on maximum every couple of weeks even in the summer. Why? Because most of the time, even in the summer, the AC system is only sort of loafing along. It needs to be run at max every so often, to maximize flow of the Freon and more importantly the oil, throughout the entire system. Of course, this depends upon where you live. For those in Vegas, probably every time you enter the car, the AC gets a full workout.
WHY RUN THE HEATER IN THE SUMMER?
The idea is to maximize the anti-corrosion ability of the anti-freeze, to prevent internal corrosion of the heater core from causing a pin-hole leak. This works best when the coolant is flowed/ flushed over the inner heater core surfaces, scouring away any minor corrosion or accumulated sediment (to prevent clogging the core). It is simply not good for the heater core to sit with stagnant coolant for 6 months.
The RDX heater core has a valve inside the inlet coolant line. Unless the heater is run at maximum, this valve is always either partly or completely closed. This limits (or prevents entirely) coolant flow through the heater core.
Although a new RDX heater core is probably only about $100, the labor to replace it is probably about 15 hours. The first step in replacing the RDX heater core, is to evacuate (remove) the Freon from the AC system, then disconnect the lines to the AC evaporator inside the car. The evaporator is sitting under the dash, just next to the heater core. Next step is to remove the dash: loosen the steering wheel shaft, disconnect all of the air bag electricals, etc. Well, I guess you get the idea.
HOW TO RUN THE HEATER IN THE SUMMER
In order to maximize the coolant flow through the heater core, the inlet hose valve must be forced completely open. The only way to do this is to set the HVAC temperature request to ‘Hi’. This places the HVAC system in manual mode. Check the Owner’s Manual. Set the fan control to minimum. I do not know if the RDX AC can be run at the same time (while the heater is on). My Chevy Blazer does allow this ‘dual’ model, which is how I do it for the Blazer.
As a suggestion, first warm the engine to normal operating temperature, and also use the AC system to cool the interior. That will limit the discomfort of running the heater when it is 100 degrees outside (or wait for a cooler day or night). It is probably not necessary to run the heater for more than a couple of minutes, and certainly not more than 5 minutes, during the summer.
But consider running the heater on HI during the winter, every so often. That will ensure maximum coolant flow through the heater core, and maximum corrosion protection, during the winter months.
CHEERS.
-----eof
The following 2 users liked this post by dcmodels:
cdub_1 (11-11-2023),
Michelle Peterfesso (03-19-2012)
07-13-2011, 03:49 PM
#3
Copy cat shinobi
It window defogger does do it, auto does it too. However DCmodels is right some people don't use their hvac system at all in the winter at all. Case in point: Blowing cold air on short trips, some people don't even warm up the family cars in the winter before driving it.
08-05-2012, 07:08 PM
#6
Burning Brakes
Thread Starter
HOW to TEMPERATURE TEST the A/C SYSTEM
A temperature test of the Air Conditioning part of the HVAC (Heating, Ventilation, and Air Conditioner) system will:
Ø Give a general indication of whether anything is wrong, before you might otherwise notice a problem, and
Ø Give a baseline value for future comparison and reference.
For example, this test can give an early indication of a slow Freon leak, by reporting a higher-than-specified A/C temperature output. If the Freon-level and pressure falls too low, the A/C compressor can be damaged before the low-pressure shut-off switch closes. The Honda/ Acura A/C systems are known for sustaining serious damage if the compressor self-destructs, and distributes metal throughout the lines and condenser, etc. You can expect a required, complete system replacement at a cost of $2K or more.
If the A/C output temperature is not within the Acura specification, then there are several other specific things to be checked, but they are not covered here. There are also a number of ACURAZINE links dealing with specific A/C problems, and how to diagnose them.
WHY PERFORM the STANDARD TEMPERATURE-CHECK of the A/C (AIR CONDITIONER)?
A butt-check for A/C temperature is not very accurate. I performed this test because my RDX does not seem to cool as well as my 14 year-old Chevy 4x4. And to be honest, after performing the RDX standard temp test, I still do not know if the RDX cools as well as the Chevy, but the RDX does cool within the required specification.
The Acura standard RDX cooling temp test differs enough from the Chevy standard test, that the two test results cannot be compared. Another time, I will perform the Chevy temp test on the RDX, as a means of comparison.
THE ACURA RDX STANDARD TEMPERATURE TEST for the A/C (AIR CONDITIONER) part of the HVAC system:
The RDX test takes less than 10 minutes and requires only an accurate temperature gauge. While the test is simple, it is different than simply measuring the A/C output temperature while driving around, or while parked. Since most people do not seem to have the FSM (factory service manual), here is the FSM test with a few notes.
Read the TEST CONDITIONS, and then follow the directions below. You will have to set the HVAC buttons after starting the engine. I first drive the vehicle to warm up, or just test after returning home in the evening from work.
TEST CONDITIONS:
Ø Avoid direct sunlight (park in the shade, but not inside a small garage). Calm (no wind) conditions are best. I park behind my own garage in the evening, outside, in the shade.
Ø Open the hood.
Ø Open (fully) both front doors.
Ø Make certain that both the FRONT WINDSHIELD DEFROST BUTTON and the REAR WINDOW DEFOGGER BUTTON are set to OFF.
Ø Set the Climate Control (HVAC) system DUAL switch OFF.
Ø Set the RECIRCULATION BUTTON to ON.
Ø Set the MODE BUTTON to VENT. There are four (4) positions for this button: VENT, BOTH, FLOOR, and FLOOR/ DEFROSTER. The VENT position shows a single arrow pointing at the top (face) of the seated-figure.
Ø Turn the A/C SWITCH to ON, and the FAN CONTROL to MAX speed.
Ø Using the TEMPERATURE CONTROL BUTTON (arrows) set the temperature to MAX COOL (Lo reading).
Ø Hold the engine speed at 1,500rpm.
Ø No driver or passengers in vehicle. I set the emergency brake, gear-shift to Neutral, and balance a small tool box on the accelerator. Just be sure that the engine RPM is not too high (or low).
PROCEDURE:
1) Determine the relative humidity, and the ambient temperature (in the shade). Record for later reference.
2) Park the vehicle in the shade, and setup the control conditions.
3) Open the glove box. Detach the hook (A) of the damper, then press the glove box stop (C) on each side inward, then let the glove box (B) hang down (same as when you change the Cabin Filter).
PICTURE: open glove box
4) Position a thermometer near the blower unit’s recirculation inlet duct (B). I just lay it on top of the back of the glove-box.
PICTURE: thermometer positions
5) Start the engine, and adjust to 1,500rpm. After about 3 minutes the thermometer in the inlet duct should stabilize. Record the reading. Note that thermometer reading-stabilization my require longer with a slow reading thermometer.
6) Move the thermometer to the center vent (A). After another 3 minutes the reading should stabilize. Record the reading. The FSM states to run the A/C for 10 minutes before taking the two temperature readings. That requires two thermometers. Also, I did run the A/C for 10 minutes, but did not notice any different temp readings after more than 3-minutes. That was probably because the car had already been driven 30 minutes and 10 miles before I started the test.
7) DONE. Shut off the engine and close the doors and hood, and the glove-box.
MY OWN TEST RESULTS:
The ambient air temperature was 89°F and the relative humidity was about 35%. I was sitting in the driver’s seat, which is contrary to the required STANDARD TEST CONDITIONS. There was a cross-wind through the open doors, which is why I was sitting inside the car, in the driver’s seat (to help block the wind).
The blower recirculation inlet (VENT DELIVERY) temperature was 89°F and the vent outlet temperature was 46°F.
HOW TO READ YOUR OWN TEST RESULTS:
The following graph is taken from the Acura RDX FSM. You can print it for later reference, or just read it online, to compare your own A/C readings. Note that the ambient air temperature is not used, but only the air inlet temperature at the blower recirculation inlet.
I am not certain why the ambient air temperature outside of the vehicle is taken, but I suppose it is an interesting piece of information, the difference between the outside ambient air temp and the blower inlet temp (also called the VENT DELIVERY TEMP in the chart below).
Where the RED INTAKE TEMP line of 89°F crosses the WHITE RELATIVE HUMIDITY of 35%, shows the MAXIMUM OUTPUT TEMPERATURE allowed for a good test of the A/C system, which from the chart is 48°F (BLACK line). My actual measured RED OUTPUT TEMP was 46°F, so that is a good (but not great) result.
PICTURE: A/C output temperature chart
HOW TO GET ACCURATE VALID READINGS:
You need a fairly accurate thermometer, and you need to reference the relative humidity. Otherwise, your A/C readings will not be valid.
THERMOMETER CHOICE and SELECTION:
Please note that you can use any type of accurate thermometer: glass (bulb with mercury), bi-metallic, etc. I prefer the all metal type as I break everything that can be broken (by accident of course).
The thermometer I used was purchased from a local cooking pots-and-pans type store. It is an instant-read bi-metallic type with a stainless steel probe, an enclosed sheath/ cover for the tip, with a clip on the cover, which is useful for clipping to a vent or handling the thermometer. It has a 1-inch round plastic magnified analog dial, with 2°F markings, which is easy to read. It cost under $15.
My thermometer reads from about 0°F to 220°F, so that it is also useful for testing the HVAC heater output temperature, as well as testing an engine thermostat. By the way, instant read means a valid read in under 30 seconds. Other thermometers can take up to 2-3 minutes to get an accurate reading.
If you check the online web-site for the brand and specific thermometer that you want to purchase, you can find one that is pretty accurate. You can also purchase cooking bi-metallic thermometers online.
CALIBRATING your THERMOMETER:
For additional how-to calibration instructions, link and scroll down to the bottom of the page.
http://www.fsis.usda.gov/Factsheets/Kitchen_Thermometers/index.asp
Calibrate your thermometer at both 32°F and 212°F, and then correct your readings near these two temperatures by the required amount. For example, if your thermometer reads 34°F when it should read 32°F, then you must subtract 2°F from all of your readings. Or if your thermometer can be adjusted (mine can), then adjust by the amount that the reading is off.
You need to carefully read the instructions that came with your own thermometer, for calibration adjustment instructions, and to determine how far the end must be inserted for an accurate reading. My own thermometer probe has an indent two inches from the probe-tip, and the end MUST be inserted past the indent, when inserted into water or other medium.
32°F CALIBRATION of your THERMOMETER:
Water freezes at 32°F, so this is an easy point to check the accuracy of your thermometer. Fill a tall container with food-grade ice, and cover with distilled water and stir well. Insert your thermometer the correct amount into the container, but touching neither the bottom nor the sides, and take a reading after 3-5 minutes. Stir the thermometer probe a bit just before taking the reading.
For ease in handling, the stem of the food thermometer can be placed through the clip section of the stem sheath and, holding the sheath horizontally, the stem lowered into the water.
Most bi-metallic thermometers will have an adjustment nut on the back of the dial. Without removing the stem/ probe from the water, hold the nut with a small ignition wrench, and turn the dial-head to read 32°F. I also paint a line on the nut/ dial-back with red finger-nail polish. That way, I can tell if the adjustment nut ever is accidentally altered/ moved.
PICTURE: thermometer calibration at 32 degrees
212°F CALIBRATION of your THERMOMETER:
Water boils at 212°F, but only at sea-level and 1-atmosphere pressure. So you will find it difficult to calibrate any thermometer at this temperature. For example, where I live the boiling point of water varies between 203°F and 205°F, depending upon the exact altitude and barometric pressure. I was able to obtain the altitude and current barometric pressure, where I live, from an online local weather site.
Distilled water should be used when boiling, for the most accurate reading. Tap-water in unknown conditions (altitude/ barometric pressure), can produce a reading that is as much as 5°F low. The water must be brought to a full rolling-boil.
If you have already adjusted your thermometer at 32°F, then do not re-set your thermometer to 212°F, but just take note of the temperature offset so that your high-temp readings can be properly corrected.
AMBIENT AIR TEMPERATURE:
Use your own thermometer to test the ambient air temperature. Make certain that the reading has stabilized, by placing the thermometer in place for at least 10 minutes. The RDX vehicle temperature reading is not accurate enough for this A/C temp test, although this is an opportunity to calibrate the vehicle temp gauge reading. However, do note that unless you just drove into the test position, the vehicle temp reading may not be accurate. The vehicle needs to be moving in order to report an accurate temp reading.
RELATIVE HUMIDITY:
Unless you have your own instrument for checking humidity, you can get the data from an online source for your area, or sometimes there are telephone numbers that you can call. Or perhaps you can just check the TV local weather report.
CHEERS.
---eof
A temperature test of the Air Conditioning part of the HVAC (Heating, Ventilation, and Air Conditioner) system will:
Ø Give a general indication of whether anything is wrong, before you might otherwise notice a problem, and
Ø Give a baseline value for future comparison and reference.
For example, this test can give an early indication of a slow Freon leak, by reporting a higher-than-specified A/C temperature output. If the Freon-level and pressure falls too low, the A/C compressor can be damaged before the low-pressure shut-off switch closes. The Honda/ Acura A/C systems are known for sustaining serious damage if the compressor self-destructs, and distributes metal throughout the lines and condenser, etc. You can expect a required, complete system replacement at a cost of $2K or more.
If the A/C output temperature is not within the Acura specification, then there are several other specific things to be checked, but they are not covered here. There are also a number of ACURAZINE links dealing with specific A/C problems, and how to diagnose them.
WHY PERFORM the STANDARD TEMPERATURE-CHECK of the A/C (AIR CONDITIONER)?
A butt-check for A/C temperature is not very accurate. I performed this test because my RDX does not seem to cool as well as my 14 year-old Chevy 4x4. And to be honest, after performing the RDX standard temp test, I still do not know if the RDX cools as well as the Chevy, but the RDX does cool within the required specification.
The Acura standard RDX cooling temp test differs enough from the Chevy standard test, that the two test results cannot be compared. Another time, I will perform the Chevy temp test on the RDX, as a means of comparison.
THE ACURA RDX STANDARD TEMPERATURE TEST for the A/C (AIR CONDITIONER) part of the HVAC system:
The RDX test takes less than 10 minutes and requires only an accurate temperature gauge. While the test is simple, it is different than simply measuring the A/C output temperature while driving around, or while parked. Since most people do not seem to have the FSM (factory service manual), here is the FSM test with a few notes.
Read the TEST CONDITIONS, and then follow the directions below. You will have to set the HVAC buttons after starting the engine. I first drive the vehicle to warm up, or just test after returning home in the evening from work.
TEST CONDITIONS:
Ø Avoid direct sunlight (park in the shade, but not inside a small garage). Calm (no wind) conditions are best. I park behind my own garage in the evening, outside, in the shade.
Ø Open the hood.
Ø Open (fully) both front doors.
Ø Make certain that both the FRONT WINDSHIELD DEFROST BUTTON and the REAR WINDOW DEFOGGER BUTTON are set to OFF.
Ø Set the Climate Control (HVAC) system DUAL switch OFF.
Ø Set the RECIRCULATION BUTTON to ON.
Ø Set the MODE BUTTON to VENT. There are four (4) positions for this button: VENT, BOTH, FLOOR, and FLOOR/ DEFROSTER. The VENT position shows a single arrow pointing at the top (face) of the seated-figure.
Ø Turn the A/C SWITCH to ON, and the FAN CONTROL to MAX speed.
Ø Using the TEMPERATURE CONTROL BUTTON (arrows) set the temperature to MAX COOL (Lo reading).
Ø Hold the engine speed at 1,500rpm.
Ø No driver or passengers in vehicle. I set the emergency brake, gear-shift to Neutral, and balance a small tool box on the accelerator. Just be sure that the engine RPM is not too high (or low).
PROCEDURE:
1) Determine the relative humidity, and the ambient temperature (in the shade). Record for later reference.
2) Park the vehicle in the shade, and setup the control conditions.
3) Open the glove box. Detach the hook (A) of the damper, then press the glove box stop (C) on each side inward, then let the glove box (B) hang down (same as when you change the Cabin Filter).
PICTURE: open glove box
4) Position a thermometer near the blower unit’s recirculation inlet duct (B). I just lay it on top of the back of the glove-box.
PICTURE: thermometer positions
5) Start the engine, and adjust to 1,500rpm. After about 3 minutes the thermometer in the inlet duct should stabilize. Record the reading. Note that thermometer reading-stabilization my require longer with a slow reading thermometer.
6) Move the thermometer to the center vent (A). After another 3 minutes the reading should stabilize. Record the reading. The FSM states to run the A/C for 10 minutes before taking the two temperature readings. That requires two thermometers. Also, I did run the A/C for 10 minutes, but did not notice any different temp readings after more than 3-minutes. That was probably because the car had already been driven 30 minutes and 10 miles before I started the test.
7) DONE. Shut off the engine and close the doors and hood, and the glove-box.
MY OWN TEST RESULTS:
The ambient air temperature was 89°F and the relative humidity was about 35%. I was sitting in the driver’s seat, which is contrary to the required STANDARD TEST CONDITIONS. There was a cross-wind through the open doors, which is why I was sitting inside the car, in the driver’s seat (to help block the wind).
The blower recirculation inlet (VENT DELIVERY) temperature was 89°F and the vent outlet temperature was 46°F.
HOW TO READ YOUR OWN TEST RESULTS:
The following graph is taken from the Acura RDX FSM. You can print it for later reference, or just read it online, to compare your own A/C readings. Note that the ambient air temperature is not used, but only the air inlet temperature at the blower recirculation inlet.
I am not certain why the ambient air temperature outside of the vehicle is taken, but I suppose it is an interesting piece of information, the difference between the outside ambient air temp and the blower inlet temp (also called the VENT DELIVERY TEMP in the chart below).
Where the RED INTAKE TEMP line of 89°F crosses the WHITE RELATIVE HUMIDITY of 35%, shows the MAXIMUM OUTPUT TEMPERATURE allowed for a good test of the A/C system, which from the chart is 48°F (BLACK line). My actual measured RED OUTPUT TEMP was 46°F, so that is a good (but not great) result.
PICTURE: A/C output temperature chart
HOW TO GET ACCURATE VALID READINGS:
You need a fairly accurate thermometer, and you need to reference the relative humidity. Otherwise, your A/C readings will not be valid.
THERMOMETER CHOICE and SELECTION:
Please note that you can use any type of accurate thermometer: glass (bulb with mercury), bi-metallic, etc. I prefer the all metal type as I break everything that can be broken (by accident of course).
The thermometer I used was purchased from a local cooking pots-and-pans type store. It is an instant-read bi-metallic type with a stainless steel probe, an enclosed sheath/ cover for the tip, with a clip on the cover, which is useful for clipping to a vent or handling the thermometer. It has a 1-inch round plastic magnified analog dial, with 2°F markings, which is easy to read. It cost under $15.
My thermometer reads from about 0°F to 220°F, so that it is also useful for testing the HVAC heater output temperature, as well as testing an engine thermostat. By the way, instant read means a valid read in under 30 seconds. Other thermometers can take up to 2-3 minutes to get an accurate reading.
If you check the online web-site for the brand and specific thermometer that you want to purchase, you can find one that is pretty accurate. You can also purchase cooking bi-metallic thermometers online.
CALIBRATING your THERMOMETER:
For additional how-to calibration instructions, link and scroll down to the bottom of the page.
http://www.fsis.usda.gov/Factsheets/Kitchen_Thermometers/index.asp
Calibrate your thermometer at both 32°F and 212°F, and then correct your readings near these two temperatures by the required amount. For example, if your thermometer reads 34°F when it should read 32°F, then you must subtract 2°F from all of your readings. Or if your thermometer can be adjusted (mine can), then adjust by the amount that the reading is off.
You need to carefully read the instructions that came with your own thermometer, for calibration adjustment instructions, and to determine how far the end must be inserted for an accurate reading. My own thermometer probe has an indent two inches from the probe-tip, and the end MUST be inserted past the indent, when inserted into water or other medium.
32°F CALIBRATION of your THERMOMETER:
Water freezes at 32°F, so this is an easy point to check the accuracy of your thermometer. Fill a tall container with food-grade ice, and cover with distilled water and stir well. Insert your thermometer the correct amount into the container, but touching neither the bottom nor the sides, and take a reading after 3-5 minutes. Stir the thermometer probe a bit just before taking the reading.
For ease in handling, the stem of the food thermometer can be placed through the clip section of the stem sheath and, holding the sheath horizontally, the stem lowered into the water.
Most bi-metallic thermometers will have an adjustment nut on the back of the dial. Without removing the stem/ probe from the water, hold the nut with a small ignition wrench, and turn the dial-head to read 32°F. I also paint a line on the nut/ dial-back with red finger-nail polish. That way, I can tell if the adjustment nut ever is accidentally altered/ moved.
PICTURE: thermometer calibration at 32 degrees
212°F CALIBRATION of your THERMOMETER:
Water boils at 212°F, but only at sea-level and 1-atmosphere pressure. So you will find it difficult to calibrate any thermometer at this temperature. For example, where I live the boiling point of water varies between 203°F and 205°F, depending upon the exact altitude and barometric pressure. I was able to obtain the altitude and current barometric pressure, where I live, from an online local weather site.
Distilled water should be used when boiling, for the most accurate reading. Tap-water in unknown conditions (altitude/ barometric pressure), can produce a reading that is as much as 5°F low. The water must be brought to a full rolling-boil.
If you have already adjusted your thermometer at 32°F, then do not re-set your thermometer to 212°F, but just take note of the temperature offset so that your high-temp readings can be properly corrected.
AMBIENT AIR TEMPERATURE:
Use your own thermometer to test the ambient air temperature. Make certain that the reading has stabilized, by placing the thermometer in place for at least 10 minutes. The RDX vehicle temperature reading is not accurate enough for this A/C temp test, although this is an opportunity to calibrate the vehicle temp gauge reading. However, do note that unless you just drove into the test position, the vehicle temp reading may not be accurate. The vehicle needs to be moving in order to report an accurate temp reading.
RELATIVE HUMIDITY:
Unless you have your own instrument for checking humidity, you can get the data from an online source for your area, or sometimes there are telephone numbers that you can call. Or perhaps you can just check the TV local weather report.
CHEERS.
---eof
09-03-2012, 12:18 AM
#7
Burning Brakes
Thread Starter
TEMPERATURE TEST of MY OWN A/C SYSTEM
The following graph shows the actual measurements for my own 2009 RDX A/C system, measurements taken during August 2012, over a period of 3 weeks.
PICTURE: factory service manual A/C temperature test graph
ABOUT THE GRAPH:
The graph from the FSM (factory service manual), as shown in my previous post, has only the 80% and 30% humidity lines marked – the edges of the shaded black area.
Based on my own measurements, I have added the lines to the graph above to make it easier for me to decide if my RDX A/C system is performing to specification. And to make it easier to compare future readings to the current ones.
The white lines and the individual black lines, are extrapolated values (my best guesses), as shown on the graph. Note how the humidity readings vary non-linearly by temperature, on the graph. Also note that just because 32°F output is shown on the graph, there is nothing in the FSM to indicate that the RDX A/C can actually deliver that output temperature at any specific input temperature or relative humidity, under the specified test conditions.
ABOUT THE FSM TEST PROCEDURE FOR A/C TEMPERATURE:
The purpose of the Acura RDX test procedure is not to determine just how cold the A/C can produce air, under an arbitrary condition. The idea is to determine the maximum A/C output under heavily loaded conditions. That is the reason why the test is performed with opened RDX vehicle doors.
You can observe from the Acura A/C temperature graph that high humidity loads/ stresses an A/C system much more than low humidity. The problem is that at lower ambient temperatures below 80 degrees, and at lower humidity levels below 30%, the A/C compressor is not heavily loaded. So instead of running constantly, the compressor cycles on/ off. That means that a test performed under these conditions does not give a true indication of the A/C system capability. That is probably why only the BLACK area on the graph is defined.
I have performed the tests above, as a baseline for myself, for future reference, to determine if my own A/C system is still working as well as it does now. So, you will need to perform your own test of your own A/C system, and compare against the FSM graph to determine how well your A/C system is working. Or you can compare against my own readings as a reference point, if your readings fall outside the defined FSM graph BLACK area..
ABOUT MY OWN MEASUREMENTS:
Unless it is about to rain, or actually raining, the weather conditions where I live never fall within the specified shaded black area of the FSM graph for A/C temperatures.
In August, days are typically 95-100 degrees with a relative humidity of 10-20%. Nights are typically 65-75 degrees with a relative humidity of 30-40%. And I am not going to try taking an A/C temp measurement at 3am – the neighbors would surely complain.
Also, the measurements that I did take, may not seem consistent with the Humidity lines on the graph. Compare the two measurements that I took at 19% and 20% humidity. The two readings do not fit ‘neatly’ into the graph.
The temperature readings that I took are valid. The only way to get an accurate humidity reading next to the vehicle is with your own humidity meter – but I am too cheap to buy one. As for the humidity readings that I used and the problems with getting an accurate humidity reading, please see the next section below.
DIFFICULTY WITH HUMIDITY READINGS:
Unless you have your own humidity meter, you must relay upon a 3rd party reading. I use an online web site which lists the humidity for my city/ area for approximately every 5 minutes for the previous 3 days. I do not know where you live, but where I live, weather conditions can change extremely rapidly. For example, I ran a specific A/C temp test at 5:30pm, and the relative humidity was 20% at 93°F.
At 7:00pm the humidity was still 20% at 91°F, but at 7:30pm the humidity was 59% at 77°F. That is because rain-clouds blew in, but as usual in the desert, it never did rain that evening. And the barometric pressure changed from 29.96 to 30.02 during the same period, a clear indication of weather change.
Note from the FSM A/C temperature graph that a change from 20% to 59% relative humidity completely alters the validity of the INPUT/ OUTPUT A/C temperature test. That means you must get an accurate relative humidity value, at the specific time of your test, to validate your A/C temperature test.
There is an additional problem where I live, which is in a large valley. The temperature and humidity readings are taken at one corner of the valley. But one side, or one end of the valley, can have completely different weather conditions from the other side or end. It can be raining in one part of the valley, and sunny in another. And I do not live right next to the weather station.
This variation in weather by location where I live, probably accounts for the fact that the A/C readings shown in my own graph above, vary a bit from absolute consistency with the graph humidity lines.
WHERE CAN YOU GET AN ACCURATE HUMIDITY READING?
Here is a link where you can find the RELATIVE HUMIDITY for your own city/ area. Relative Humidity does not change with altitude, at least not from sea level up to around 10,000 feet. So a reading near your address will probably be fairly accurate for your A/C temperature test.
http://w1.weather.gov – enter City/ State, then look around on the new page and click on “3-DAY HISTORY”
A NOTE ABOUT THERMOMETERS:
The thermometer that I used in these tests, is rated as shatter-proof. But it is certainly not shock-proof. I accidentally dropped it onto the cement floor of my garage. I had to re-calibrate it, and it was off by three degrees at 32 degrees.
RDX HVAC DOOR FUNCTION CHECK:
NOTE: the FSM manual states that the temperature difference between the two dash side vents (by the front door hinges) should be less than 20°F. That seems like a ridiculous large difference, to me.
But checking the temp difference between the two side vents, will let you know if there is any problem in the RDX HVAC mix-door control system, especially if you also perform the check with the DUAL button both ON and OFF, but with the TEMP and VENT settings the same for both driver and passenger sides. Two thermometers would make this check easier.
MY CONCLUSION:
After several temperature tests, I conclude that there is not much reserve power in the RDX A/C system, that is, not much additional cooling power over the minimum specified factory performance – at least not at low humidity levels below 30%.
At another time, if there is some day (locally) when the humidity is above 30% (during the daytime), I will perform this test again. I wonder how the RDX A/C system performs in Houston, Texas where I grew up. It is not unusual for the summer temperature to be 105°F with a relative humidity of 95% or more. Yes, it is like swimming in air. According to the FSM graph, the RDX A/C will be lucky to cool the air much below 80°F under these conditions. I now understand why my brother routinely sets his A/C to MAX COOL, to dry-out the air.
If anyone else should perform this test, I would be interested whether your results are similar to mine?
-----eof
The following graph shows the actual measurements for my own 2009 RDX A/C system, measurements taken during August 2012, over a period of 3 weeks.
PICTURE: factory service manual A/C temperature test graph
ABOUT THE GRAPH:
The graph from the FSM (factory service manual), as shown in my previous post, has only the 80% and 30% humidity lines marked – the edges of the shaded black area.
Based on my own measurements, I have added the lines to the graph above to make it easier for me to decide if my RDX A/C system is performing to specification. And to make it easier to compare future readings to the current ones.
The white lines and the individual black lines, are extrapolated values (my best guesses), as shown on the graph. Note how the humidity readings vary non-linearly by temperature, on the graph. Also note that just because 32°F output is shown on the graph, there is nothing in the FSM to indicate that the RDX A/C can actually deliver that output temperature at any specific input temperature or relative humidity, under the specified test conditions.
ABOUT THE FSM TEST PROCEDURE FOR A/C TEMPERATURE:
The purpose of the Acura RDX test procedure is not to determine just how cold the A/C can produce air, under an arbitrary condition. The idea is to determine the maximum A/C output under heavily loaded conditions. That is the reason why the test is performed with opened RDX vehicle doors.
You can observe from the Acura A/C temperature graph that high humidity loads/ stresses an A/C system much more than low humidity. The problem is that at lower ambient temperatures below 80 degrees, and at lower humidity levels below 30%, the A/C compressor is not heavily loaded. So instead of running constantly, the compressor cycles on/ off. That means that a test performed under these conditions does not give a true indication of the A/C system capability. That is probably why only the BLACK area on the graph is defined.
I have performed the tests above, as a baseline for myself, for future reference, to determine if my own A/C system is still working as well as it does now. So, you will need to perform your own test of your own A/C system, and compare against the FSM graph to determine how well your A/C system is working. Or you can compare against my own readings as a reference point, if your readings fall outside the defined FSM graph BLACK area..
ABOUT MY OWN MEASUREMENTS:
Unless it is about to rain, or actually raining, the weather conditions where I live never fall within the specified shaded black area of the FSM graph for A/C temperatures.
In August, days are typically 95-100 degrees with a relative humidity of 10-20%. Nights are typically 65-75 degrees with a relative humidity of 30-40%. And I am not going to try taking an A/C temp measurement at 3am – the neighbors would surely complain.
Also, the measurements that I did take, may not seem consistent with the Humidity lines on the graph. Compare the two measurements that I took at 19% and 20% humidity. The two readings do not fit ‘neatly’ into the graph.
The temperature readings that I took are valid. The only way to get an accurate humidity reading next to the vehicle is with your own humidity meter – but I am too cheap to buy one. As for the humidity readings that I used and the problems with getting an accurate humidity reading, please see the next section below.
DIFFICULTY WITH HUMIDITY READINGS:
Unless you have your own humidity meter, you must relay upon a 3rd party reading. I use an online web site which lists the humidity for my city/ area for approximately every 5 minutes for the previous 3 days. I do not know where you live, but where I live, weather conditions can change extremely rapidly. For example, I ran a specific A/C temp test at 5:30pm, and the relative humidity was 20% at 93°F.
At 7:00pm the humidity was still 20% at 91°F, but at 7:30pm the humidity was 59% at 77°F. That is because rain-clouds blew in, but as usual in the desert, it never did rain that evening. And the barometric pressure changed from 29.96 to 30.02 during the same period, a clear indication of weather change.
Note from the FSM A/C temperature graph that a change from 20% to 59% relative humidity completely alters the validity of the INPUT/ OUTPUT A/C temperature test. That means you must get an accurate relative humidity value, at the specific time of your test, to validate your A/C temperature test.
There is an additional problem where I live, which is in a large valley. The temperature and humidity readings are taken at one corner of the valley. But one side, or one end of the valley, can have completely different weather conditions from the other side or end. It can be raining in one part of the valley, and sunny in another. And I do not live right next to the weather station.
This variation in weather by location where I live, probably accounts for the fact that the A/C readings shown in my own graph above, vary a bit from absolute consistency with the graph humidity lines.
WHERE CAN YOU GET AN ACCURATE HUMIDITY READING?
Here is a link where you can find the RELATIVE HUMIDITY for your own city/ area. Relative Humidity does not change with altitude, at least not from sea level up to around 10,000 feet. So a reading near your address will probably be fairly accurate for your A/C temperature test.
http://w1.weather.gov – enter City/ State, then look around on the new page and click on “3-DAY HISTORY”
A NOTE ABOUT THERMOMETERS:
The thermometer that I used in these tests, is rated as shatter-proof. But it is certainly not shock-proof. I accidentally dropped it onto the cement floor of my garage. I had to re-calibrate it, and it was off by three degrees at 32 degrees.
RDX HVAC DOOR FUNCTION CHECK:
NOTE: the FSM manual states that the temperature difference between the two dash side vents (by the front door hinges) should be less than 20°F. That seems like a ridiculous large difference, to me.
But checking the temp difference between the two side vents, will let you know if there is any problem in the RDX HVAC mix-door control system, especially if you also perform the check with the DUAL button both ON and OFF, but with the TEMP and VENT settings the same for both driver and passenger sides. Two thermometers would make this check easier.
MY CONCLUSION:
After several temperature tests, I conclude that there is not much reserve power in the RDX A/C system, that is, not much additional cooling power over the minimum specified factory performance – at least not at low humidity levels below 30%.
At another time, if there is some day (locally) when the humidity is above 30% (during the daytime), I will perform this test again. I wonder how the RDX A/C system performs in Houston, Texas where I grew up. It is not unusual for the summer temperature to be 105°F with a relative humidity of 95% or more. Yes, it is like swimming in air. According to the FSM graph, the RDX A/C will be lucky to cool the air much below 80°F under these conditions. I now understand why my brother routinely sets his A/C to MAX COOL, to dry-out the air.
If anyone else should perform this test, I would be interested whether your results are similar to mine?
-----eof
Trending Topics
01-28-2013, 12:02 AM
#8
Burning Brakes
Thread Starter
HOW to - HEATER OUTPUT TEMPERATURE TEST
A standardized temperature test of the HEATER part of the HVAC (Heating, Ventilation, and Air Conditioner) system will:
Ø Give a general indication of whether something is wrong, before you might otherwise notice a problem, and in time to repair a minor problem before it becomes a major problem, and
Ø Give a baseline test result value for future comparison and reference.
The 2009 Acura RDX factory service manual (FSM) does not provide a standard temperature output test or specifications for the HEATER, although it does so for the A/C system. But all modern vehicle HVAC systems function in a similar manner, regardless of the difference in the physical and electronic configurations between vehicle brands and even different car models of the same brand. Therefore, similar test results may be expected, and a test of my Acura 2009 RDX heater provided similar results to a test of my GM 1998 truck heater.
Note that the test procedure presented here, is based directly upon the GM 1998 S10 vehicles, as presented in the 1998 S-10 FSM S/T TRUCK SERVICE MANUAL, second edition, published 10/23/98.
The temperature test procedure below will require about 30 minutes, must be performed while driving, and requires only an accurate thermometer. The test procedure is simple, and gives accurate and repeatable results.
Please read completely though this post, before attempting to perform the test procedure. It will take you much longer to read this post, than to perform the test procedure. But unless you read completely through this post, and understand it, your test results will not be valid.
WHAT’S COVERED in this POST?
Ø WHY POST THIS TEST PROCEDURE?
Ø WHY PERFORM the STANDARD TEMPERATURE-CHECK of the HEATER?
Ø WHAT ARE THE CONSEQUENCES IF THE HEATER TEMPERATURE OUTPUT IS TOO LOW?
Ø COMPONENT CHECKS BEFORE PERFORMING THE FSM STANDARD HEATER TEST:
Ø BEFORE YOU PERFORM THE GM STANDARD TEST, VERIFY THAT YOUR HVAC CONTROLS ARE FUNCTIONING PROPERLY:
Ø MY COMMENTS ABOUT TESTING THE HVAC SYSTEM:
Ø SAFETY FIRST DURING THE TEST PROCEDURE:
Ø THE GM STANDARD PERFORMANCE TEMPERATURE TEST for the HEATER part of the HVAC system:
Ø MY OWN ACURA RDX TEST RESULTS:
Ø WHAT CAN YOU DO TO HELP PREVENT HEATER and HVAC PROBLEMS?
WHY POST THIS TEST PROCEDURE?
I have read a number of posts complaining of low heat output, and people wondering just how much heat various Acura vehicles should produce, and under what conditions, and what might cause a low heater temperature. This post will attempt to give the reader some help. Sorry, but mostly what I have read online regarding expected temperature output of the heater is conjecture, guessing at best.
WHY PERFORM the STANDARD TEMPERATURE-CHECK of the HEATER?
Always begin a problem diagnosis with the easiest test. By the time you notice that the HEATER system is not performing as it once did, you already have a serious problem, possibly a plugged heater core. But there are several other problem possibilities. A butt-check for heater temperature output is just not accurate enough.
The GM standard temperature procedure test is a much more severe load check of the HEATER system than a simple temp check.
But a standard test of the heater temperature output is a good place to begin. The test can give an early indication of:
Ø A partially frozen-open engine coolant thermostat. That will not allow the engine coolant to reach the specified temperature, causing the heater air output to be lower than expected.
Ø A faulty radiator cap, which does not seal and allow pressure to build to the specified 14-18psi. That would allow the engine coolant to boil at a lower than specified temperature, and the engine may not reach its specified high temperature.
Ø A partially plugged heater core.
Ø A faulty (malfunctioning) heater core water (coolant) control valve. If the valve does not open, no water flows through the heater core, and there is no heat from the HVAC vents.
Ø A problem with the driver side vent control motor, which also opens and closes the heater core water valve.
Ø A problem with one of the four (4) HVAC climate motors (including the driver side vent control motor), or the associated vent-door control linkages.
Ø A problem with one of the electronic HVAC controls (AKA buttons)
WHAT ARE THE CONSEQUENCES IF THE HEATER TEMPERATURE OUTPUT IS TOO LOW?
Well, you can back-flush the heater core before it plugs closed completely, or begins to leak from corrosion. Keeping the coolant system clean and filled with fresh coolant, is the best preventative measure you can take, to prevent future problems with the HVAC heating system.
A faulty and leaking heater core coolant control valve can be replaced, before unnoticed loss of coolant leads to an overheated engine.
COMPONENT CHECKS BEFORE PERFORMING THE FSM STANDARD HEATER TEST:
1) Inspect the outer surfaces of the radiator and the A/C condenser cores. Inspect between the condenser and the radiator as well as the outer surfaces. Ensure that the airflow is not blocked by the following materials:
DIRT
LEAVES
OTHER FOREIGN MATTER
2) Inspect the following components for restrictions (bent cooling vanes) or (hose) kinks or (hose) connector leaks:
THE A/C CONDENSER CORE
THE RADIATOR CORE
THE COOLANT HOSES, BOTH RADIATOR AND HEATER
Note that there are a number of coolant hoses that also connect to the turbo-charger. As difficult as it may be, all coolant hose connections must be checked very carefully for even minor leaks. If more than very minor occasional top-up of the radiator overflow tank is required, there is a coolant leak somewhere.
A minor coolant leak can prevent proper pressurization of the system, and low engine operating temperature. That means a low heater temperature output. And a more significant coolant leak can lead to a low coolant level, and an overheated engine.
BEFORE YOU PERFORM THE GM STANDARD TEST, VERIFY THAT YOUR HVAC CONTROLS ARE FUNCTIONING PROPERLY:
You will simply not be able to determine if there is really a problem with the heater system, unless all of the HVAC controls, lights, vents, motor controlled doors, etc. are properly working. There are three ways to check the proper functioning of the HVAC system:
Ø Operate all of the various HVAC controls, and verify that the proper response occurs. Read the Owner’s Manual for proper operation of the HVAC controls. For example, in both SINGLE and DUAL modes, verify that all HVAC lights (LEDs) are functional, and that all blower speed selections operate. Choose all of the different vent selections, and verify that air is directed correctly. Verify air flow to the rear sections of the vehicle, through the vents under the front seats. Remove any items under the front seats, which can block air flow to the rear. Etc.
Ø LINK: https://acurazine.com/forums/showthread.php?t=682368 – post #19 describes HVAC system motor and door noise troubleshooting – or consider it verification of proper operation.
Ø LINK: https://acurazine.com/forums/showthread.php?t=684991 – post #4 describes how to run the Climate Control System self-diagnostic function. Note that while running the test procedure is straight-forward, interpretation of the results requires information contained in the FSM (factory service manual), but that would be the subject of another post – or you can purchase your own FSM.
MY COMMENTS ABOUT TESTING THE HVAC SYSTEM:
The test procedure will give a good idea of the health of the HEATER portion of the HVAC system. And the results will be similar for most any modern vehicle, not just the RDX. The results will tell you if there is any problem with your HVAC system, but not necessarily which specific component is bad. More diagnosis may be required.
So, if you wish to test a vehicle other than the RDX, just read the test procedure below, and set the HVAC controls in your own vehicle, based upon the control descriptions, rather than the specific *names* on the HVAC controls. That is because the actual control buttons/ knobs and names, may differ depending upon the vehicle brand, and whether you have a manual type or electronic type HVAC option in your own vehicle.
SAFETY FIRST DURING THE TEST PROCEDURE:
PLEASE DO NOT ATTEMPT TO READ THE THERMOMETER (heater output) WHILE DRIVING – an accident is certain to occur.
The heater temperature test must be performed while driving the vehicle. This is most safely done with two people, one to drive and one to observe the heater temperature output. However, if like myself, you perform the test without a helper, please observe some basic safety measures.
Yes, I am aware that the following suggestions are only ‘common-sense’, but sometimes sense is not so common. I am not assuming that you are stupid, but only that you may not have fully considered what can happen if you do not take a few simple precautions.
The vehicle must be driven at 30mph to give an accurate heater output-temperature reading. Choose a wide side street where you can drive at that constant speed, without obstructing or being obstructed by heavy traffic. When ready to take a temperature reading, carefully pull to the curb, in a safe parking spot, and stop. Place the trans in PARK (RDX) or NEUTRAL (if manual trans) and set the emergency brake. Then quickly read the thermometer.
You may need to repeat this process a couple or three times, to get a consistent reading. Once the vehicle is stopped, the heater output temperature may begin to rapidly change, depending upon the outside ambient temperature.
THE GM STANDARD PERFORMANCE TEMPERATURE TEST for the HEATER part of the HVAC system:
The full test itself takes about 30 minutes and requires only an accurate temperature gauge. While the test is simple, it is different than simply measuring the HEATER output temperature while driving around, or while parked.
STANDARD GM HEATER TEMPERATURE OUTPUT TABLE
The following table is taken from the GM 1998 S10 FSM, with extrapolations shown in RED, the extrapolations being computed as directed in the FSM. The heater output is the MINIMUM expected temperature. Anything less would indicate a problem. And of course, the higher the heater output, the better the operation of the HVAC system.
OUTSIDE AIR TEMP .. MINIMUM HEATER AIR TEMPERATURE
-18C (0°F) ........ 54C (130°F)
-xxC (5°F) ........ xxC (131.8°F)
-xxC (10°F) ....... xxC (133.6°F)
-xxC (15°F) ....... xxC (135.4°F)
-xxC (20°F) ....... xxC (137.2°F)
-04C (25°F) ....... 59C (139°F)
-xxC (30°F) ....... xxC (140.8°F)
xxC (35°F) ........ xxC (142.6°F)
xxC (40°F) ........ xxC (144.4°F)
xxC (45°F) ........ xxC (146.2°F)
10C (50°F) ........ 64C (147°F)
xxC (55°F) ........ xxC (148.6°F)
xxC (60°F) ........ xxC (150.2°F)
xxC (65°F) ........ xxC (151.8°F)
xxC (70°F) ........ xxC (153.4°F)
24C (75°F) ........ 68C (155°F)
VERIFY THAT THE ENGINE THERMOSTAT FUNCTIONS PROPERLY:
Unless the engine coolant thermostat operates correctly, the heater output temperature will not match the expected level indicated in the table above. The next step from the GM FSM is to determine that the thermostat is closed when the engine is cold, and opens when the engine reaches normal operating temperature. If the thermostat opens too early, or is frozen open, then the engine never reaches normal operating temperature, and the heater output will be too low.
Thermostat function verification can be performed separately from the actual heater output temp check. You can either allow the engine to idle until the radiator fans run, or just drive the vehicle a short distance, about 5-10 minutes is usually sufficient.
The standard ACURA RDX engine thermostat is a 195°F nominal specification: it begins to open at 169-176°F and is completely open at 194°F, according to the Acura RDX FSM. Therefore, any normal engine coolant temperature reading should be about 195°F.
Use of a thermal/ infra-red laser thermometer is recommended for checking the engine coolant thermostat function. Take your reading from the thermostat housing, located in the lower radiator hose, bolted to the engine block. But keep in mind that any laser thermometer costing under $100 will likely have an accuracy of only +/- 4°F at best. That is a range of 191-199°F, if the actual temp is 195°F.
Another option is the use of colored melting wax pencils – one at 190°F and one at 200°F. For a normal engine temp and proper thermostat operation, the lower temp pencil should melt, and the higher temp pencil should not melt.
Note that the RDX has a very inaccurate temperature gauge. My own 2009 RDX instrument-display shows 7-bars at ‘normal’ temperature. Actually, it always display 7-bars, after a short warm-up, no matter what the ambient or the driving conditions, from an ambient of zero to 110°F. Since normal engine coolant temp is 195°F then each of the 7-bars represents a range of about 30°F. That is too great a range to represent an accurate engine temperature.
8-bars would (may) be very near to overheating, which is considered 224°F, at which time a beeper will sound, and a instrument panel light will blink. Or the temp gauge may be non-linear, and more than 8-bars may be required to indicate overheating. There is no clear definition of what (how many bars) the gauge should display for a hot engine.
WHEN THE ENGINE IS ABOVE 199°F BOTH RDX RADIATOR FANS SHOULD RUN AT HIGH SPEED. That is the only part of the FSM that seems clear (to me). Both fans have a HI and LO speed.
The RDX FSM has a table(s) describing operation of the radiator and A/C condenser fans. I have read that table many times, and have never been able to decide just when (at what temperature) either fan is supposed to run, in HI and LO speed. I assume that like most tech manuals, the RDX FSM was definitely *not* written by an engineer. If someone would like to start another thread, and discuss & explain the specified fan operation, that would be good.
SET THE HVAC CONTROLS TO THE FOLLOWING for the TEMPERATURE TEST PROCEDURE:
Ø DUAL button = OFF
Ø WINDSHIELD DEFROSTER button = OFF
Ø REAR WINDOW DEFOGGER button = OFF
Ø A/C button = OFF
Ø TEMPERATURE CONTROL button = HI (maximum)
Ø RECIRCULATION = OFF
Ø MODE button = lower vents only (or upper vents only, if driver is checking the output tempearture)
Ø FAN CONTROL button = HI (maximum)
FSM HEATER TEMPERATURE CHECK:
The following test is taken verbatim from the GM Chevy S10 FSM, with my notes in RED.
1. warm up the engine for about 20 minutes with the engine running. I find that simply driving about 5 miles at 30-40 mph, even when the temperature is 25°F, will warm the engine to normal temperature. Do not yet set the HVAC heater controls to maximum. Wait until the engine is warm, and you are ready to perform the test. But allow the HVAC system to warm up the vehicle interior, while warming the engine. There is no need to torture yourself, and a warm interior will have no effect on the maximum output of the heater. I simply set the HVAC to auto and 72-74°F.
2. drive the vehicle at 48 km/h (30 mph)
3. use an accurate thermometer in order to determine the temperature of the outside air and the temperature of the air discharged at the floor outlets. Place your thermometer in the passenger side floor vent outlet. The vent location is actually sort of under the bottom of the glove-box. I could not find a way to clip my thermometer in place, but a passenger can possibly hold it, or perhaps it can be taped in place. For my own test, I put my thermometer in the driver-side dash center-vent, and set the MODE control accordingly (upper vents only).
4. the vehicle temperature gauge which measures the ambient outside air temperature, can be used, and that is what I have done. However, you need to calibrate your vehicle’s onboard temp gauge. It can be off as much as plus or minus 5-10°F
5. otherwise, you will need to use your own separate thermometer to take an ambient air reading. Please note that the temperature inside your garage, or right next to your home/ apartment, will not be accurate.
6. to perform the test, set the HVAC TEMPERATURE to HI/ MAX, the blower speed to HIGH, the vents to FLOOR (or DASH), and the RECIRCULATION mode to OFF.
7. drive about 5 minutes or so, then stop and read the floor vent thermometer. Be aware that if you leave the heater temperature on HIGH for an extended period, even if the HVAC RECIRCULATION mode is OFF, that the vehicle interior temperature will rapidly increase. You will not get an accurate measurement of the heater core output, but a measurement affected by the accumulated heat inside the insulated vehicle cabin.
8. note that the heater output temp difference, between the (almost) maximum heater control-setting, and the actual maximum control-setting, can be as much as 30°F.
MY OWN ACURA RDX TEST RESULTS:
The following are the test results from my own Acura 2009 RDX with about 30K miles. I do not know how accurate is the coolant temperature gauge in my own vehicle, but the following are the actual readings. The second reading was taken to demonstrate how the recirculation mode incorrectly affects the test results. All readings were taken from the driver’s side center-dash vent, with ALL dash vents fully opened.
04 Jan 2013: RDX HEATER = 150°F, ambient = 20°F, engine coolant = 7bars, RECIRCULATION = OFF
04 Jan 2013: RDX HEATER = 162°F, ambient = 20°F, engine coolant = 7bars, RECIRCULATION = ON
As a comparison, the following are the test results from my own GM 1998 Chevy truck with about 110K miles. Notice how the heater output temperature can be affected by the engine coolant temperature. All readings were taken from the passenger side floor vent.
02 Dec 2011: Chevy HEATER = 165°F, ambient = 32°F, engine coolant = 190°F, 108K miles
20 Dec 2012: Chevy HEATER = 155-160°F, ambient = 27°F, engine coolant = 183°F, 113K miles, night
21 Dec 2012: Chevy HEATER = 154-158°F, ambient = 43°F, engine coolant = 186°F, 113K miles, daytime
The range in the Chevy heater output, is most likely because after stopping the vehicle, I have to remove the thermometer from the heater vent on the passenger side floor, in order to see it properly. The reading on the fast-read thermometer, drops pretty quickly. So I repeated the tests a couple of times, getting slightly different readings each time.
The lower engine temp for the later (date) test results, may indicate a weak/ failing engine coolant thermostat. Over the years, my Chevy thermostat has failed (frozen open) at least twice. All of the thermostats used have been OEM from GM, purchased at the dealer. Next time I plan to use an aftermarket one.
WHAT CAN YOU DO TO HELP PREVENT HEATER and HVAC PROBLEMS?
The RDX has a heater coolant valve, which controls coolant flow through the heater core. Coolant flows through the heater core, only when the valve is open.
RUN THE HEATER ONCE A WEEK IN THE SUMMER:
Running the heater, even during the summer, will exercise the HVAC vent control system, both the electrical motor-driven doors and levers, as well as the water (coolant) valve. Just slowly move the temperature setting from low to high and back, at least once.
Allow the HVAC system to operate in the high heat position for at least 5 minutes. That will allow the coolant to scour any corrosion and sludge from the inside of the heater-core, which is like a coolant mini-radiator.
But do *not* use the absolute lowest or highest settings. See the next section. I feel that it is better to discover a stuck vent-door or sticking control-lever arm in the summer, rather than in December.
CAUTION AGAINST USING THE HVAC HIGHEST (or LOWEST) TEMPERATURE SETTINGS:
Setting the HVAC to the absolute max-heat (Hi) or max-cool (Lo) positions can (potentially) cause one or more of the HVAC vent-door control motors to move past the intended max-positions, damaging either their gears (plastic) or the connected positioning-levers (also plastic). The control-motors drive only back-and-forth, within a limited range, instead of continuously in a circle like a ‘normal’ motor.
Obviously, overdriving the vent-doors is not supposed to happen. But it takes just one ECC (electronic climate control) computer hiccup to cause a problem. So I recommend using the heating/ cooling setting that is just one-step less than the actual maximums: 86°F and 58°F respectively.
Of course, you must use the MAX (Hi) heat setting in order to test the heater temp output. But otherwise there is really no reason to use the MAX heat setting.
DO NOT RUN THE A/C WHEN THE TEMPERATURE IS BELOW 40°F
There is a low-temp sensor, which is supposed to prevent the A/C compressor from running, when the ambient (outside air) is below 38°F. However, if that sensor should fail to function properly, the compressor may run anyway. This can damage the compressor, and is the purpose of the sensor and cut-out switch. So for safety, just do not try to run the A/C system when the outside temp is very low.
CHEERS.
A standardized temperature test of the HEATER part of the HVAC (Heating, Ventilation, and Air Conditioner) system will:
Ø Give a general indication of whether something is wrong, before you might otherwise notice a problem, and in time to repair a minor problem before it becomes a major problem, and
Ø Give a baseline test result value for future comparison and reference.
The 2009 Acura RDX factory service manual (FSM) does not provide a standard temperature output test or specifications for the HEATER, although it does so for the A/C system. But all modern vehicle HVAC systems function in a similar manner, regardless of the difference in the physical and electronic configurations between vehicle brands and even different car models of the same brand. Therefore, similar test results may be expected, and a test of my Acura 2009 RDX heater provided similar results to a test of my GM 1998 truck heater.
Note that the test procedure presented here, is based directly upon the GM 1998 S10 vehicles, as presented in the 1998 S-10 FSM S/T TRUCK SERVICE MANUAL, second edition, published 10/23/98.
The temperature test procedure below will require about 30 minutes, must be performed while driving, and requires only an accurate thermometer. The test procedure is simple, and gives accurate and repeatable results.
Please read completely though this post, before attempting to perform the test procedure. It will take you much longer to read this post, than to perform the test procedure. But unless you read completely through this post, and understand it, your test results will not be valid.
WHAT’S COVERED in this POST?
Ø WHY POST THIS TEST PROCEDURE?
Ø WHY PERFORM the STANDARD TEMPERATURE-CHECK of the HEATER?
Ø WHAT ARE THE CONSEQUENCES IF THE HEATER TEMPERATURE OUTPUT IS TOO LOW?
Ø COMPONENT CHECKS BEFORE PERFORMING THE FSM STANDARD HEATER TEST:
Ø BEFORE YOU PERFORM THE GM STANDARD TEST, VERIFY THAT YOUR HVAC CONTROLS ARE FUNCTIONING PROPERLY:
Ø MY COMMENTS ABOUT TESTING THE HVAC SYSTEM:
Ø SAFETY FIRST DURING THE TEST PROCEDURE:
Ø THE GM STANDARD PERFORMANCE TEMPERATURE TEST for the HEATER part of the HVAC system:
Ø MY OWN ACURA RDX TEST RESULTS:
Ø WHAT CAN YOU DO TO HELP PREVENT HEATER and HVAC PROBLEMS?
WHY POST THIS TEST PROCEDURE?
I have read a number of posts complaining of low heat output, and people wondering just how much heat various Acura vehicles should produce, and under what conditions, and what might cause a low heater temperature. This post will attempt to give the reader some help. Sorry, but mostly what I have read online regarding expected temperature output of the heater is conjecture, guessing at best.
WHY PERFORM the STANDARD TEMPERATURE-CHECK of the HEATER?
Always begin a problem diagnosis with the easiest test. By the time you notice that the HEATER system is not performing as it once did, you already have a serious problem, possibly a plugged heater core. But there are several other problem possibilities. A butt-check for heater temperature output is just not accurate enough.
The GM standard temperature procedure test is a much more severe load check of the HEATER system than a simple temp check.
But a standard test of the heater temperature output is a good place to begin. The test can give an early indication of:
Ø A partially frozen-open engine coolant thermostat. That will not allow the engine coolant to reach the specified temperature, causing the heater air output to be lower than expected.
Ø A faulty radiator cap, which does not seal and allow pressure to build to the specified 14-18psi. That would allow the engine coolant to boil at a lower than specified temperature, and the engine may not reach its specified high temperature.
Ø A partially plugged heater core.
Ø A faulty (malfunctioning) heater core water (coolant) control valve. If the valve does not open, no water flows through the heater core, and there is no heat from the HVAC vents.
Ø A problem with the driver side vent control motor, which also opens and closes the heater core water valve.
Ø A problem with one of the four (4) HVAC climate motors (including the driver side vent control motor), or the associated vent-door control linkages.
Ø A problem with one of the electronic HVAC controls (AKA buttons)
WHAT ARE THE CONSEQUENCES IF THE HEATER TEMPERATURE OUTPUT IS TOO LOW?
Well, you can back-flush the heater core before it plugs closed completely, or begins to leak from corrosion. Keeping the coolant system clean and filled with fresh coolant, is the best preventative measure you can take, to prevent future problems with the HVAC heating system.
A faulty and leaking heater core coolant control valve can be replaced, before unnoticed loss of coolant leads to an overheated engine.
COMPONENT CHECKS BEFORE PERFORMING THE FSM STANDARD HEATER TEST:
1) Inspect the outer surfaces of the radiator and the A/C condenser cores. Inspect between the condenser and the radiator as well as the outer surfaces. Ensure that the airflow is not blocked by the following materials:
DIRT
LEAVES
OTHER FOREIGN MATTER
2) Inspect the following components for restrictions (bent cooling vanes) or (hose) kinks or (hose) connector leaks:
THE A/C CONDENSER CORE
THE RADIATOR CORE
THE COOLANT HOSES, BOTH RADIATOR AND HEATER
Note that there are a number of coolant hoses that also connect to the turbo-charger. As difficult as it may be, all coolant hose connections must be checked very carefully for even minor leaks. If more than very minor occasional top-up of the radiator overflow tank is required, there is a coolant leak somewhere.
A minor coolant leak can prevent proper pressurization of the system, and low engine operating temperature. That means a low heater temperature output. And a more significant coolant leak can lead to a low coolant level, and an overheated engine.
BEFORE YOU PERFORM THE GM STANDARD TEST, VERIFY THAT YOUR HVAC CONTROLS ARE FUNCTIONING PROPERLY:
You will simply not be able to determine if there is really a problem with the heater system, unless all of the HVAC controls, lights, vents, motor controlled doors, etc. are properly working. There are three ways to check the proper functioning of the HVAC system:
Ø Operate all of the various HVAC controls, and verify that the proper response occurs. Read the Owner’s Manual for proper operation of the HVAC controls. For example, in both SINGLE and DUAL modes, verify that all HVAC lights (LEDs) are functional, and that all blower speed selections operate. Choose all of the different vent selections, and verify that air is directed correctly. Verify air flow to the rear sections of the vehicle, through the vents under the front seats. Remove any items under the front seats, which can block air flow to the rear. Etc.
Ø LINK: https://acurazine.com/forums/showthread.php?t=682368 – post #19 describes HVAC system motor and door noise troubleshooting – or consider it verification of proper operation.
Ø LINK: https://acurazine.com/forums/showthread.php?t=684991 – post #4 describes how to run the Climate Control System self-diagnostic function. Note that while running the test procedure is straight-forward, interpretation of the results requires information contained in the FSM (factory service manual), but that would be the subject of another post – or you can purchase your own FSM.
MY COMMENTS ABOUT TESTING THE HVAC SYSTEM:
The test procedure will give a good idea of the health of the HEATER portion of the HVAC system. And the results will be similar for most any modern vehicle, not just the RDX. The results will tell you if there is any problem with your HVAC system, but not necessarily which specific component is bad. More diagnosis may be required.
So, if you wish to test a vehicle other than the RDX, just read the test procedure below, and set the HVAC controls in your own vehicle, based upon the control descriptions, rather than the specific *names* on the HVAC controls. That is because the actual control buttons/ knobs and names, may differ depending upon the vehicle brand, and whether you have a manual type or electronic type HVAC option in your own vehicle.
SAFETY FIRST DURING THE TEST PROCEDURE:
PLEASE DO NOT ATTEMPT TO READ THE THERMOMETER (heater output) WHILE DRIVING – an accident is certain to occur.
The heater temperature test must be performed while driving the vehicle. This is most safely done with two people, one to drive and one to observe the heater temperature output. However, if like myself, you perform the test without a helper, please observe some basic safety measures.
Yes, I am aware that the following suggestions are only ‘common-sense’, but sometimes sense is not so common. I am not assuming that you are stupid, but only that you may not have fully considered what can happen if you do not take a few simple precautions.
The vehicle must be driven at 30mph to give an accurate heater output-temperature reading. Choose a wide side street where you can drive at that constant speed, without obstructing or being obstructed by heavy traffic. When ready to take a temperature reading, carefully pull to the curb, in a safe parking spot, and stop. Place the trans in PARK (RDX) or NEUTRAL (if manual trans) and set the emergency brake. Then quickly read the thermometer.
You may need to repeat this process a couple or three times, to get a consistent reading. Once the vehicle is stopped, the heater output temperature may begin to rapidly change, depending upon the outside ambient temperature.
THE GM STANDARD PERFORMANCE TEMPERATURE TEST for the HEATER part of the HVAC system:
The full test itself takes about 30 minutes and requires only an accurate temperature gauge. While the test is simple, it is different than simply measuring the HEATER output temperature while driving around, or while parked.
STANDARD GM HEATER TEMPERATURE OUTPUT TABLE
The following table is taken from the GM 1998 S10 FSM, with extrapolations shown in RED, the extrapolations being computed as directed in the FSM. The heater output is the MINIMUM expected temperature. Anything less would indicate a problem. And of course, the higher the heater output, the better the operation of the HVAC system.
OUTSIDE AIR TEMP .. MINIMUM HEATER AIR TEMPERATURE
-18C (0°F) ........ 54C (130°F)
-xxC (5°F) ........ xxC (131.8°F)
-xxC (10°F) ....... xxC (133.6°F)
-xxC (15°F) ....... xxC (135.4°F)
-xxC (20°F) ....... xxC (137.2°F)
-04C (25°F) ....... 59C (139°F)
-xxC (30°F) ....... xxC (140.8°F)
xxC (35°F) ........ xxC (142.6°F)
xxC (40°F) ........ xxC (144.4°F)
xxC (45°F) ........ xxC (146.2°F)
10C (50°F) ........ 64C (147°F)
xxC (55°F) ........ xxC (148.6°F)
xxC (60°F) ........ xxC (150.2°F)
xxC (65°F) ........ xxC (151.8°F)
xxC (70°F) ........ xxC (153.4°F)
24C (75°F) ........ 68C (155°F)
VERIFY THAT THE ENGINE THERMOSTAT FUNCTIONS PROPERLY:
Unless the engine coolant thermostat operates correctly, the heater output temperature will not match the expected level indicated in the table above. The next step from the GM FSM is to determine that the thermostat is closed when the engine is cold, and opens when the engine reaches normal operating temperature. If the thermostat opens too early, or is frozen open, then the engine never reaches normal operating temperature, and the heater output will be too low.
Thermostat function verification can be performed separately from the actual heater output temp check. You can either allow the engine to idle until the radiator fans run, or just drive the vehicle a short distance, about 5-10 minutes is usually sufficient.
The standard ACURA RDX engine thermostat is a 195°F nominal specification: it begins to open at 169-176°F and is completely open at 194°F, according to the Acura RDX FSM. Therefore, any normal engine coolant temperature reading should be about 195°F.
Use of a thermal/ infra-red laser thermometer is recommended for checking the engine coolant thermostat function. Take your reading from the thermostat housing, located in the lower radiator hose, bolted to the engine block. But keep in mind that any laser thermometer costing under $100 will likely have an accuracy of only +/- 4°F at best. That is a range of 191-199°F, if the actual temp is 195°F.
Another option is the use of colored melting wax pencils – one at 190°F and one at 200°F. For a normal engine temp and proper thermostat operation, the lower temp pencil should melt, and the higher temp pencil should not melt.
Note that the RDX has a very inaccurate temperature gauge. My own 2009 RDX instrument-display shows 7-bars at ‘normal’ temperature. Actually, it always display 7-bars, after a short warm-up, no matter what the ambient or the driving conditions, from an ambient of zero to 110°F. Since normal engine coolant temp is 195°F then each of the 7-bars represents a range of about 30°F. That is too great a range to represent an accurate engine temperature.
8-bars would (may) be very near to overheating, which is considered 224°F, at which time a beeper will sound, and a instrument panel light will blink. Or the temp gauge may be non-linear, and more than 8-bars may be required to indicate overheating. There is no clear definition of what (how many bars) the gauge should display for a hot engine.
WHEN THE ENGINE IS ABOVE 199°F BOTH RDX RADIATOR FANS SHOULD RUN AT HIGH SPEED. That is the only part of the FSM that seems clear (to me). Both fans have a HI and LO speed.
The RDX FSM has a table(s) describing operation of the radiator and A/C condenser fans. I have read that table many times, and have never been able to decide just when (at what temperature) either fan is supposed to run, in HI and LO speed. I assume that like most tech manuals, the RDX FSM was definitely *not* written by an engineer. If someone would like to start another thread, and discuss & explain the specified fan operation, that would be good.
SET THE HVAC CONTROLS TO THE FOLLOWING for the TEMPERATURE TEST PROCEDURE:
Ø DUAL button = OFF
Ø WINDSHIELD DEFROSTER button = OFF
Ø REAR WINDOW DEFOGGER button = OFF
Ø A/C button = OFF
Ø TEMPERATURE CONTROL button = HI (maximum)
Ø RECIRCULATION = OFF
Ø MODE button = lower vents only (or upper vents only, if driver is checking the output tempearture)
Ø FAN CONTROL button = HI (maximum)
FSM HEATER TEMPERATURE CHECK:
The following test is taken verbatim from the GM Chevy S10 FSM, with my notes in RED.
1. warm up the engine for about 20 minutes with the engine running. I find that simply driving about 5 miles at 30-40 mph, even when the temperature is 25°F, will warm the engine to normal temperature. Do not yet set the HVAC heater controls to maximum. Wait until the engine is warm, and you are ready to perform the test. But allow the HVAC system to warm up the vehicle interior, while warming the engine. There is no need to torture yourself, and a warm interior will have no effect on the maximum output of the heater. I simply set the HVAC to auto and 72-74°F.
2. drive the vehicle at 48 km/h (30 mph)
3. use an accurate thermometer in order to determine the temperature of the outside air and the temperature of the air discharged at the floor outlets. Place your thermometer in the passenger side floor vent outlet. The vent location is actually sort of under the bottom of the glove-box. I could not find a way to clip my thermometer in place, but a passenger can possibly hold it, or perhaps it can be taped in place. For my own test, I put my thermometer in the driver-side dash center-vent, and set the MODE control accordingly (upper vents only).
4. the vehicle temperature gauge which measures the ambient outside air temperature, can be used, and that is what I have done. However, you need to calibrate your vehicle’s onboard temp gauge. It can be off as much as plus or minus 5-10°F
5. otherwise, you will need to use your own separate thermometer to take an ambient air reading. Please note that the temperature inside your garage, or right next to your home/ apartment, will not be accurate.
6. to perform the test, set the HVAC TEMPERATURE to HI/ MAX, the blower speed to HIGH, the vents to FLOOR (or DASH), and the RECIRCULATION mode to OFF.
7. drive about 5 minutes or so, then stop and read the floor vent thermometer. Be aware that if you leave the heater temperature on HIGH for an extended period, even if the HVAC RECIRCULATION mode is OFF, that the vehicle interior temperature will rapidly increase. You will not get an accurate measurement of the heater core output, but a measurement affected by the accumulated heat inside the insulated vehicle cabin.
8. note that the heater output temp difference, between the (almost) maximum heater control-setting, and the actual maximum control-setting, can be as much as 30°F.
MY OWN ACURA RDX TEST RESULTS:
The following are the test results from my own Acura 2009 RDX with about 30K miles. I do not know how accurate is the coolant temperature gauge in my own vehicle, but the following are the actual readings. The second reading was taken to demonstrate how the recirculation mode incorrectly affects the test results. All readings were taken from the driver’s side center-dash vent, with ALL dash vents fully opened.
04 Jan 2013: RDX HEATER = 150°F, ambient = 20°F, engine coolant = 7bars, RECIRCULATION = OFF
04 Jan 2013: RDX HEATER = 162°F, ambient = 20°F, engine coolant = 7bars, RECIRCULATION = ON
As a comparison, the following are the test results from my own GM 1998 Chevy truck with about 110K miles. Notice how the heater output temperature can be affected by the engine coolant temperature. All readings were taken from the passenger side floor vent.
02 Dec 2011: Chevy HEATER = 165°F, ambient = 32°F, engine coolant = 190°F, 108K miles
20 Dec 2012: Chevy HEATER = 155-160°F, ambient = 27°F, engine coolant = 183°F, 113K miles, night
21 Dec 2012: Chevy HEATER = 154-158°F, ambient = 43°F, engine coolant = 186°F, 113K miles, daytime
The range in the Chevy heater output, is most likely because after stopping the vehicle, I have to remove the thermometer from the heater vent on the passenger side floor, in order to see it properly. The reading on the fast-read thermometer, drops pretty quickly. So I repeated the tests a couple of times, getting slightly different readings each time.
The lower engine temp for the later (date) test results, may indicate a weak/ failing engine coolant thermostat. Over the years, my Chevy thermostat has failed (frozen open) at least twice. All of the thermostats used have been OEM from GM, purchased at the dealer. Next time I plan to use an aftermarket one.
WHAT CAN YOU DO TO HELP PREVENT HEATER and HVAC PROBLEMS?
The RDX has a heater coolant valve, which controls coolant flow through the heater core. Coolant flows through the heater core, only when the valve is open.
RUN THE HEATER ONCE A WEEK IN THE SUMMER:
Running the heater, even during the summer, will exercise the HVAC vent control system, both the electrical motor-driven doors and levers, as well as the water (coolant) valve. Just slowly move the temperature setting from low to high and back, at least once.
Allow the HVAC system to operate in the high heat position for at least 5 minutes. That will allow the coolant to scour any corrosion and sludge from the inside of the heater-core, which is like a coolant mini-radiator.
But do *not* use the absolute lowest or highest settings. See the next section. I feel that it is better to discover a stuck vent-door or sticking control-lever arm in the summer, rather than in December.
CAUTION AGAINST USING THE HVAC HIGHEST (or LOWEST) TEMPERATURE SETTINGS:
Setting the HVAC to the absolute max-heat (Hi) or max-cool (Lo) positions can (potentially) cause one or more of the HVAC vent-door control motors to move past the intended max-positions, damaging either their gears (plastic) or the connected positioning-levers (also plastic). The control-motors drive only back-and-forth, within a limited range, instead of continuously in a circle like a ‘normal’ motor.
Obviously, overdriving the vent-doors is not supposed to happen. But it takes just one ECC (electronic climate control) computer hiccup to cause a problem. So I recommend using the heating/ cooling setting that is just one-step less than the actual maximums: 86°F and 58°F respectively.
Of course, you must use the MAX (Hi) heat setting in order to test the heater temp output. But otherwise there is really no reason to use the MAX heat setting.
DO NOT RUN THE A/C WHEN THE TEMPERATURE IS BELOW 40°F
There is a low-temp sensor, which is supposed to prevent the A/C compressor from running, when the ambient (outside air) is below 38°F. However, if that sensor should fail to function properly, the compressor may run anyway. This can damage the compressor, and is the purpose of the sensor and cut-out switch. So for safety, just do not try to run the A/C system when the outside temp is very low.
CHEERS.
06-13-2014, 07:10 PM
#9
Burning Brakes
Thread Starter
REPLACE MISSING PICTUREs FOR A/C TEST:
Sadly, using a hosting site for posting pics, means that eventually they *disappear*. So this time I am posting them directly on this site, which now means you must login to see them.
Sadly, using a hosting site for posting pics, means that eventually they *disappear*. So this time I am posting them directly on this site, which now means you must login to see them.
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mada51589
3G TL Problems & Fixes
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