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I'll have to take some time to go through some of that testing. But, to answer your question, I checked both the A.C. clutch relay and the A.C. fan relay. The radiator fan seems to be working fine, so did not check that relay.
Does it make sense that the AC fan not running would result in intermittent cooling?
Also, would you mind elaborating on how to cross connect positions 1 and 2 of the relay?
Thanks again.
Here is a thread with a diagram of the relay socket, numbered. To jump 1 and 2, means to remove the relay and electrically connect them.
The relays are powered before ignition, I activated both fans with the key in position II, without the engine running just by pushing A.C. on inside the cabin
First test the fan, use a cable to power directly the fan from the battery. This tells you whether it can even run or not.
The A.C. fan should activate if/when A.C. is active, to pull enough air to cool off the condenser in front of the radiator.
Is the A.C. cooling off the cabin? If yes then it's probably just the fan itself.
The worst situation could be A.C. on at idle in stop/go traffic with hot sunny conditions, warming up the condenser without its second fan, while radiator struggles to cool off the engine.
Keep an eye on the temperature especially at idle, run the cabin full HEAT, at any sign of increasing temperature, that runs the coolant through the cabin heater and reduces the load of the radiator.
On my 2008 base, without exact display of temperature in the dashboard, the stable temp is 7 bars in the dashboard lcd display, yours might be different. I use a dongle to connect my phone to the car information for more exact data.
Both fans should turn on when you push the A.C. cabin button on. You are correct in testing without delay to find and fix the problem.
Yes - it cools the cabin sometimes. At other times it just blows hot air.
I checked the engine temp yesterday in 90 degree weather. It seemed to be stable at a normal temp.
Sounds like it could just just be the fan. Maybe a dumb question, but is there an easy way to access the fan connector to test it? Seems like it’s at the bottom of the fan..
Yes - it cools the cabin sometimes. At other times it just blows hot air.
I checked the engine temp yesterday in 90 degree weather. It seemed to be stable at a normal temp.
Sounds like it could just just be the fan. Maybe a dumb question, but is there an easy way to access the fan connector to test it? Seems like it’s at the bottom of the fan..
thanks
Blowing hot at times: check A.C. , if low on coolant agent, may have to reload somewhat to reach operating parameters.
I remember reaching over top of radiator, maybe because my wire is loose, no longer tied. The airshield under the bumper cover is EASILY accessible, held by some 8-10 pins. Use a screwdriver to lift each pinhead FIRST then entire pin can be pulled out easily by fingers. Once the airdam is loose you can reach the connector from below as well. I used zip ties to replace some aged&broken pins.
In the same area there is the connector to the rad temperature sensor. If jumped on the end towards the engine should activate the other fan, another item to cross off the list items to check if you want too.
If the fuses are all good in both under hood panels and under dash panel. Then check that Freon level. If that’s good then check to see if the fans turn on and off with the climate control. Then check the clutch on the compressor by turning on the as to see if it spins freely. Check for clunking noises or no noses at all.
On a 2007 1G RDX would a delay for the A/C to come on, 5-8 minutes be a symptom of bad relay? I've replaced mine 2 or 3x so far and have about 110K Miles.
On a 2007 1G RDX would a delay for the A/C to come on, 5-8 minutes be a symptom of bad relay?
Hi!
The relay failures were described initially as failing either closed (leading to much higher pressure levels, resulting in forced venting of coolant agent and loss of cooling capacity) or open (example the fan relay not activating the radiator fan when required). Have not seen threads describing a delay in their failures.
Once the AC button activates, both radiator fan and condenser fan turn on- easy to verify visually looking at them, the clutch should activate the compressor (easy to verify visually looking down along the belt towards the bottom of engine for the compressor clutch face-has three large bolts, if it does not move it is not engaging) This all immediate, not delayed. Cold air may take some time to be felt through the vents, 10-15 seconds.
Thanks Altair. I guess I was hoping for the easy fix that was fixed in the past. I’m an electronics guy so, electronics problems are easier for me to work with.
It it turns out, or rather doesn’t turn.... the clutch is kicking in intermittently and compressor is not spinning but fan spinning seems ok. Should I make a new thread/post?
but the problem is intermittent. I’m not sure if cooler weather and the clutch turning on is coincidental or not. I may jumper the relay to see if there something before the relay causing the problem. I did replace my MAF intake manifold this winter. Any thoughts?
... the clutch is kicking in intermittently and compressor is not spinning but fan spinning seems ok. Should I make a new thread/post?...
but the problem is intermittent. I’m not sure if cooler weather and the clutch turning on ... Any thoughts?
Seems you had past trouble with the relay, sorry it didn't hold. Based on your details both fans activate so you can count the relay as working, unless of course you can prove otherwise.
Compressor not spinning or working during cooler weather matches symptoms for the clutch spacer... small washer to be added or removed... EXPLAINS the symptoms link to outside temperature
Suggest testing the clutch circuit first, to rule out the electrical/electronics possibilities.
There is at least a thread dealing with the mechanical part of the clutch, the spacer washer. Might save you the need for a new compressor, DIY can be done without opening the system. You may have to lift the compressor to rest on the radiator top, use a thick cardboard to protect the radiator fins!
EBay clutch replacement kit might be around 40$; I have a whole new compressor waiting for now~100$-really don't want to open system if not necessary.
Nice reference materials, will have to give them a spin soon, very curious now, thank you.
Did you try to check the pressure levels on the system with a gauge and then put in new Freon? The lube from the Freon might get it spinning again. Sometimes it freezes if it’s not at the proper amount.
Did you try to check the pressure levels on the system with a gauge and then put in new Freon? The lube from the Freon might get it spinning again. Sometimes it freezes if it’s not at the proper amount.
Thanks for the tip. I got myself an A/C PRO can w gauge and it shows in the red with the AC turned to high with car running on the low port. What would that mean?
these folks say if the compressors not engaged it will always read in the red
You can try to put some in but make sure you’re connected to the right pipe and location. It sounds like you’re compressor may have died like mine did around 140k
I’m at 112k. Makes sense just to get an aftermarket compressor kit for $300 bucks and replace. How much do you think a mechanic will charge to replace?
I’m at 112k. Makes sense just to get an aftermarket compressor kit for $300 bucks and replace. How much do you think a mechanic will charge to replace?
Are you sure it's the Compressor, not the clutch or the field coil? Consider that clutch replacement may not require opening of the system, same for field coil replacement.
I have seen recommendations may have to recover the refridgerant first, replace other parts as well if&when you open the system, as required by compressor replacement, see discussion below (ignore details&pricing specific to a different car), followed by reloading of oil and agent.
I was about to order a clutch, but I tested the coil by jumpering the relay and it clicks and engages when engine is running. However, it’s not cooling. Low side is about 40 psi with refill gauge. So either the pressure is off, or something else. I’m guessing it’s not the a/c pressure sensor, since it’s probably doing it’s job
one odd thing is getting a P0113 OBD code for air intake temperature sensor high. I’m not sure if that has anything to do with the a/c circuit.
Thanks. It seems like he didn’t test the relays correctly and the system needed more refrigerant and the cheap gauge reads higher than it is. My theory is that the extreme heat has expanded the refrigerant and is causing the sensor to keep the compressor from turning on.
should the passenger side fan be blowing always? It was blowing a while back intermittently, but it didn’t turn today, that I saw.. headscratch...
I didn’t measure the coil bc I csn’t Get to it at this point.
Thanks. It seems like he didn’t test the relays correctly and the system needed more refrigerant and the cheap gauge reads higher than it is. My theory is that the extreme heat has expanded the refrigerant and is causing the sensor to keep the compressor from turning on.
should the passenger side fan be blowing always? It was blowing a while back intermittently, but it didn’t turn today, that I saw.. headscratch...
I didn’t measure the coil bc I csn’t Get to it at this point.
I thought passenger side is the A.C. fan, in which case it's back to square one for you if "it didn't turn today" ( i.e. fan/wiring/relay or cabin.button problem).
Test&fix fan first to immediately activate with the cabin A.C. button, engine does not need to run, both fans should immediately spin though. Also look for intermittently off moments, always on is one of the symptoms of relay failure=failed closed followed soon by release of extra pressure&loss of Freon.
You may have access to compressor terminals for measurement without taking it off.
My re-reading of it was that he was getting 45-50 psi with the cheap set, and the 70 psi with better set AFTER dealer replaced Freon and relay. At least he was in the green, yours was recently red for low pressure reading.
... I tried different fan relay combos but they still don’t spin. So strange.
I say "... So lucky.". In the dead of winter below zero, the engine in my base 08 RDX seems to reach normal temperature with just less than 3 km of driving. Without fans to cool off, it is then a matter of just few more stops&moments to overheat.
Were you keeping an eye on the temperature reported at all, exact through OBD2 or the dash line indicator?
Forget about the multi meter for now and Ground the car until at least you have the fans working and you can activate them at will while driving, as you think it's already warm enough at your location to want A.C..
Grab a 3 foot long piece of telephone wire, strip its ends, disconnect the fans, connect each fan plug with said wire directly to battery posts, replace any fan that does not spin.
Reconnect fans and jump the A.C. relay directly, if the fans don't spin with the relay jumpered the harness is suspect...
Once the fans spin, place relay back and activate the cabin switch, both fans should now spin, if not the relay or its wiring are suspect...
Repeat with a different relay in the place of suspect AC relay until both fans start turning when activating cabin switch.
Only then take your time and use the diagrams to test the clutch spacing/shims and the coil resistance. Fix and repeat.
When the spacing and resistance are both within spec, consider a visit to the A.C. shop for a test and vacuum&refill service.
If sufficient freon w fresh oil and still not working, then a compressor change might be coming your way.
Well the good news is that relay #15 upper left of 3 rows of relays jumpered turns on both fans even though it’s just supposed to be condenser fan.
Are we positive the AC cabin button should turn on both fans?
ok and the relay for the radiator fan jumpered works. I’m wondering if I should just hard wire the radiator fan for now to drive. I can easily how up 2 quick connects to a jumper wire.
All these test check out fine. Head scratch indeed
Nice, still lucky, more things to check then 😁
Originally Posted by guavatone
Well the good news is that relay #15 upper left of 3 rows of relays jumpered turns on both fans even though it’s just supposed to be condenser fan.
* I believe that is just supposed to be like that. Condenser fan is the A.C. fan on passenger side, and the relay indicated is the A.C. condenser fan as per info from this thread #28
《 hhrdx08 , 07-17-2014 12:54 PM
Thanks to dcmodels, great thread.
Could anyone show me the locations of the relays for items 3, 4, 5 & 7 listed below? TIA
3) A/C condenser Fan 4) Electronic Throttle Control System (ETCS) control 5) Radiator Fan 6) A/C compressor clutch 7) PGM-FI (programmed fuel injection) sub-relay
#29 hhrdx08 , 07-17-2014 05:46 PM
Ah, silly me. They are in the same fuse box.》*
Are we positive the AC cabin button should turn on both fans?
**positive, just retested on mine, both spin even without engine started; that is how I avoided an overheat incident last year, saw 8 tiny bars instead of normal 7 on the display, paranoid since then, seems to work for me.**
ok and the relay for the radiator fan jumpered works.
***if jumpered works and plugged relay doesn't, test the radiator temperature sensor with the relay plugged in (see below). I take it relay is a new "...05" type as you were replacing relays recently, if not mark all and switch around as per Dcmodels notes?
Retest with engine cold, key to ignition II but engine not started.***
I’m wondering if I should just hard wire the radiator fan for now to drive. I can easily how up 2 quick connects to a jumper wire.
**** that keeps you on the road, delays finding out why.
I am now confused by ...radiator fan for now to drive... (thought you worried about the condenser one as its malfunction may in turn lead the condenser to be too warm for A.C. to even work )?
Anyway, the radiator has a single temp sensor plugged into it, below, on driver side, accessible by loosening the air dam plastic -special fasteners to be first unlocked w flat screwdriver, then pulled. Unplug and jumper its' harness coming from the engine. Radiator fan should now spin by itself. If not, verify the temperature level when idling, the sensor may need to be replaced if it does not activate the fan by 213F or less ( approximate boiling point of unpressurized water).
This sensor controls the fan only; the temperature on the MID display is from a second sensor located on the block near the thermostat/top radiator hose, via the ECU, AND DOES NOT CONTROL THE FAN.
Upon cold start my 08 ( thermostat new in 2017) opens the coolant flow just past 200F and the radiator fan (looks original) activates only @212-213F, both seem high to my expectations, ymmv
Hope you have an obd2 app to monitor exact temps and let us know what you are dealing with****
Yeah. I thought about that sensor. On other hondas they have videos of people using s paper clip to short the ECT. Is there a way to do this on the RDX?
i was starting to think it’s PCM connector A5 as per diagnostic steps. I am not showing continuity between the low side of relay actuator connectors and body ground. From the diagram it looks like ground occurs through a transistor, but the schematic is incomplete.
thanks for the encouragement but i’m On the verge of giving up
i’m also still wondering if I got my MAF sensor dirty when I replace my intake this past winter.
i also noticed a weird buzzing for 10 seconds after starting on the left side under hood.
Yeah. I thought about that sensor. On other hondas they have videos of people using s paper clip to short the ECT. Is there a way to do this on the RDX?
....
thanks for the encouragement but i’m On the verge of giving up
...
Test should be very similar.
You found the critical spot, rad fan does not work with the relay, works when jumped. The upside is you likely avoided major failure as overheating is just one of potential consequences.
A) Test the sensor harness to ensure continuity,
B) Retest different relays to determine which work and which don't.
C) With good working relay, idle the engine and monitor exact temperature level, get new sensor if past 214F without activating the fan properly.
D) Examine radiator connections.
No more than 20' of simple tests until you know if you have to order sensor, and how many relays if any. Bonus: pictures to tell you if you should soon plan for a new radiator.
Here is a picture from a Honda radiator with a similar connector for the transmission oil, rust buildup on the washer surfaces:
Deal with the A.C. issue AFTER you get your car back on the road with well functioning engine cooling system.
Compare with what I did last month, dump 1 year old coolant, 3 successive refills with distilled water,
before refilling again-this fourth time with coolant, took most of the weekend (last year I replaced the 10 year old radiator plus added fresh coolant, because had found the rust on the nuts shown, in 2017 chose to replace probably original thermostat+coolant).
Have a cool drink after the tests are done, keep us posted!
I’m driving short 10 minute trips successfully under 200 F monitored with OBD app. I guess I have to test the ECT when the fluid is drained and the sensor is pulled, right?
I need an air conditioned garage. It’s too damn hot
6 gallons of distilled water from the ...mart for flushing, 3x flushes meant to bring coolant concentration down to less than 4%, had to do it third year in a row because I found stray voltage again, 0.14V-0.2xV related to the radiator, engine off and on. Was 0.0xV last year with fresh coolant.
Unfortunately found no indication of an engine drain plug to save the weekend flush work.
Have not yet tested the new coolant, prefer now to test couple months after the change, and will be buying a new mm soon just for that purpose.
Originally Posted by CSmoney28
What happens if you see rust but your temperature reads fine and both your fans are turning on?
See below:
Different issues related to same part the radiator, suggestion was to examine a cumbersome area, taking advantage of inspection work related to temperature sensor on the radiator, so much easier access to the driver connection.
Rust is an indicator that is weakening the joint in time, mine did not fail in 10 years, other honda/Acura owners were not so lucky in less time, (in the thread half reported overheating symptoms, half did not, so your guess is as good as any)
#11 and #12 have the charges in case of such failure, and only if the transmission is not malfunctioning
Should there be visible rust, joint is already weaker than from factory assembly.
GUAVATONE indicated his rad fan NOT WORKING, the situation can easily escalate to extra pressure due to fan not cooling the radiator, and placing extra strain on the fragile joints, hence my suggestion to get the fans working normally before driving the car out again.
《trent_ky 10-11-2016 03:51 PM
I wish I had known this was a potential problem before and I totally would have done this! I'm pretty sure it already has an external trans cooler anyways which is why I was surprised that the radiator also cooled the trans. I highly recommend everyone follow the above advice. I assure you that you don't want the same mess I had.》
Besides, coolant has to be drained in order for sensor to be replaced when so necessary.
There’s a bunch of Honda videos of ECT tests by shorting the cable with paper clips. Can’t this be done with the RDX by doing it on both sensors. Someone here put their sensor in boiling water to test, but it makes more sense to do the paper clip test. Right?
BTW Coolant level was hovering around minimum line, but the should be “enough”?
it it seems like it fixed it, but all the talk about fan on temperature confused me as to weather it worked. Sounds like you are having major problems Altair. So sorry.
I’m driving short 10 minute trips successfully under 200 F monitored with OBD app. I guess I have to test the ECT when the fluid is drained and the sensor is pulled, right?
I need an air conditioned garage. It’s too damn hot
That may be good news.
I hope you tested the sensor harness already? This is important step, cant skip it, verifies the circuit from the sensor through the relay to the fan...
Then test COOLANT TEMPERATURE, IDLING, WITH FLUID ALL RELAYS AND SENSOR IN PLACE, no need to drive, drain or pull anything, while watching for the radiator fan to activate. No effort required, boring actually... do not take your eyes off the temperature reading.
If temperature reaches 214F without radiator fan spinning, sensor is suspect, turn engine off.
* touch lightly/carefully each hose from the radiator, feeling for a lot of heat that should indicate the thermostat did open and the pump pushes the coolant through. If one of the hoses remains cold even at over 200F then coolant is not circulating-very unlikely as you drove 10' with a stable 200F temperature. The digital temp reading first drops quickly from just over 200F to about 186F when the thermostat opens up and without either fan cooling the radiator.
When were the belt, water pump, thermostat and coolant last changed, if you know?
* i believe the sensor lowers resistance with higher temperature, hence a jumper on the harness fools the relay to activate the fan; conversely a broken wire would disable the circuit and in turn the fan won't turn on even if sensor is working perfectly.
Its resistance profile shifts up with age, hence a drift towards higher temperatures over years;
I did not yet come across temperature range or resistance readings for new sensor, for comparison purposes.
Warning, the time to idle and activate fan from COLD START may be quite long, be patient and do not let temp to go above 214F.
If/when the fan starts working, you should see an almost immediate drop, second drop in the digital temperature reading, back down again to about 186F. Without the fan WORKING, temperature will go higher, eventually too high.
There’s a bunch of Honda videos of ECT tests by shorting the cable with paper clips. Can’t this be done with the RDX by doing it on both sensors. Someone here put their sensor in boiling water to test, but it makes more sense to do the paper clip test. Right?
BTW Coolant level was hovering around minimum line, but the should be “enough”?
Which "...both sensors."? I thought we were talking single sensor at bottom of radiator, controls the fan, use paperclip to short the sensor HARNESS from the engine end and see if fan turns on as well.
Check coolant level, cold engine, from both inside radiator and inside expansion tank.
I know the thermostat (mechanical valve) could be checked in hot water-seems complex, or just simply touch the two hoses when over 200F, can tell right away with no work involved. Not sure about the temperature sensor in hot water, without its confirmed specs hard to see how.
Originally Posted by guavatone
It seems like this is the same problem i’m Having without the a/c issue
It it seems like it fixed it, but all the talk about fan on temperature confused me as to weather it worked. Sounds like you are having major problems Altair. So sorry.
Mistryp expected his fan to turn on at 90C with new sensor but it did not, and we don't have his reading from the new sensor to show us what to expect with a new sensor.
My tests on my car with the old likely original sensor showed on@212F/100C and off@~186F. As long as my radiator fan activates, even at 212F I have maybe nothing to worry about yet (even though I also expected a lower temperature, maybe even 90C 194F like mistryp did). The specs did not quite match either of our cases, and seemed more marketing than technical reference so I ignored them too.
Does your car turn on the fan before the 213F,? This is your important answer to find...
Also check your radiator connections and read trent_ky details of its failure, could be enlighting even if don't think it's applicable to your case yet.
You see I bought my car used in 2017 with 208k km, checked it in detail and did all the required maintenance at the time, with unusual extensive details thanks to this web site.
I am returning the favor by sharing my experiences. Since then found it easy to maintain it mostly myself, no unexplained real surprises or failures.
Entertainment system works as I desire. I did manage to save the transmission from failing-story for a different day. Have no persistent overheating signs, new radiator and both fans work so far (yes I monitor the temp as often as possible), relatively good fuel mileage for its size even compared with the rest of 2008 rdx cars.
Even after replacing the TMIC and radiator I find this car CHEAPER to maintain than initially estimated.
What are my major problems, 6 gallons of distilled water @1cdn$ each plus coolant, you must be joking arent you? My posting is meant to show how to flush down the remaining coolant without taking down the water pump, as we dont have the convenience of a coolant drain plug. Even if I choose to do it every year, I show the necessary test, almost free for those interested, easy to ignore for the rest.
Don't laugh but I disconnected the HFL recently like others did too, and did not work on the A.C. system yet, despite having purchased the compressor already. Also have other fish to fry at the time.
In short love my 1st gen rdx, @264k km now.
Let us know how are you making out with the remaining tests!
06-07-2019, 10:29 AM
