AUTO Climate Control - nothing happens
Thread Starter
Instructor
Joined: Nov 2004
Posts: 163
Likes: 31
From: Fairfield, CT
AUTO Climate Control - nothing happens
I've had an issue off an on since the summer months with my '05 RL, but now seems constant. I'm in the northeast, it's winter and I typically have the CC system set to AUTO and 75 degrees to warm it up. Usually several seconds after the car is started you will hear the fans spin up, and after a few minutes you start to get heat. Now I get nothing. Nothing at all. No fans or heat. In the summer it started out as sporadic, where I would set the temperature to mid-60's and the AC would kick in after a minute or so, or increasingly not at all. The kicker is if I drop the temperature all the way down or to max, it will force it to blow cold or hot respectively, but not at full fan speed. Same for heat. Never full fan speed either- maybe a 3 or 4 setting. I can however manually set temperature, AC on/off, fan speed and direction though. It does blow both cold and hot air. It just seems the AUTO button isn't functioning properly.
Anyone experience this or have ideas? Dread taking this to the dealer, not that I wouldn't if I can't figure it out on my own, but can't stand their instant 120$ computer fee!
Anyone experience this or have ideas? Dread taking this to the dealer, not that I wouldn't if I can't figure it out on my own, but can't stand their instant 120$ computer fee!
Senior Moderator
Joined: Dec 2010
Posts: 31,897
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From: Austin, TX
It could be your interior temperature sensors failing since the AUTO mode relies completely on those for the feedback loop.
What happens if you set DUAL and have different temps on each side? Do both sides show the same symptoms?
What happens if you set DUAL and have different temps on each side? Do both sides show the same symptoms?
Thread Starter
Instructor
Joined: Nov 2004
Posts: 163
Likes: 31
From: Fairfield, CT
Thanks, that was an interesting idea. Since I so rarely use the DUAL function I didn't think to see a comparison. I had a chance to try that today, but unfortunately the results are the same either way. It was barely in the low 20's this morning when I started up the car. Flipped on AUTO, DUAL, then set a temp of 78. Waited a couple minutes, nothing. Fans never kicked in. Flipped over to manual and the fans kicked right in.
So everything does work on manual though, min/max fan speeds, min/max temperatures, AC , etc.
I'd like to find out where the interior temp sensor is, see if it's something I can replace. Went through the various service manuals, but I didn't see anything.
Thanks again for that idea though!
So everything does work on manual though, min/max fan speeds, min/max temperatures, AC , etc.
I'd like to find out where the interior temp sensor is, see if it's something I can replace. Went through the various service manuals, but I didn't see anything.
Thanks again for that idea though!
Senior Moderator
Joined: Dec 2010
Posts: 31,897
Likes: 7,251
From: Austin, TX
The driver's side is right above where your right knee would be. There is a square with horizontal slots in the plastic cover. The passenger side should be very similar.
However, I think the cances of both sides going out at once is slim. It sounds to me like the climate control module is failing. I know you can buy these used no problem and can even use the MMC controller which has mode selection and fan speed(?) added.
http://www.oemacuraparts.com/parts-c...tioner-control
Sounds like a tough issue to diagnose without an HDS unless some random member here has experienced it and chimes in.
However, I think the cances of both sides going out at once is slim. It sounds to me like the climate control module is failing. I know you can buy these used no problem and can even use the MMC controller which has mode selection and fan speed(?) added.
http://www.oemacuraparts.com/parts-c...tioner-control
Sounds like a tough issue to diagnose without an HDS unless some random member here has experienced it and chimes in.
Thread Starter
Instructor
Joined: Nov 2004
Posts: 163
Likes: 31
From: Fairfield, CT
Looks like I may have stumbled on the source of this problem today. I replaced the little light bulbs that light the CC panel, that went very well. I popped off the the drivers side temp sensor panel and it was thoroughly gunked up with dust and other airborne dirt! 
The sensor is sitting directly in front of a very small fan that pulls in sample air from the cabin. Theres no filter here. So the sensor, which looks like a small black plastic head measuring may 1/16", was completely caked. Kind of surprised because I keep my car clean, just never thought to pop that off. I cleaned it off carefully, then flipped on AUTO and it immediately responded. But still not 100%, but definitely improved.
So I tried to find the passenger side sensor, thinking thats probably just as dirty, but didn't see any pop off panel like the drivers side.
Do you happen to know where the passenger side sensor is?
The sensor is sitting directly in front of a very small fan that pulls in sample air from the cabin. Theres no filter here. So the sensor, which looks like a small black plastic head measuring may 1/16", was completely caked. Kind of surprised because I keep my car clean, just never thought to pop that off. I cleaned it off carefully, then flipped on AUTO and it immediately responded. But still not 100%, but definitely improved.So I tried to find the passenger side sensor, thinking thats probably just as dirty, but didn't see any pop off panel like the drivers side.
Do you happen to know where the passenger side sensor is?
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Senior Moderator
Joined: Dec 2010
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From: Austin, TX
Per the service manual, there is only one cabin temperature sensor (the one you cleaned). However, there are two sensors that measure the temperature of the air coming out of the vents for driver and passenger. I recommend reading the HVAC.pdf from the service manual here as it is very informative. The sensors start on page 80.
This is very interesting for diagnosing problems.
There is a table of troubleshooting info, but it won't paste correctly. This is on page 14.
This is very interesting for diagnosing problems.
Originally Posted by RL Service Manual, HVAC
Displaying Sensor Inputs at the Climate Control Unit
The climate control unit has a mode that displays sensor inputs it receives. This mode shows you what the
climate control unit is receiving from each of the sensors, one at a time, and it can help you determine if a
sensor is faulty.
Check these items before using the sensor input display mode
1. Turn the ignition switch ON (II), and check the recirculation door function; press the recirculation
button to switch from FRESH to RECIRC. The air volume and sound should change slightly.
2. Set the temperature control knob to the desired test temperature. When selecting the test temperature,
note these items:
"Lo" temperature setting will default to MAX COOL, VENT, and RECIRC.
"Hi" temperature setting will default to MAX HOT, FLOOR, and FRESH.
58 through 86°F settings will use the automatic climate control logic.
3. Turn the ignition switch OFF.
To run the sensor input display mode, follow these steps
4. Turn the ignition switch OFF.
5. Press and hold both the AUTO and recirculation buttons while starting the engine. Release the
buttons.
6. Turn the ignition switch ON (II). Use the navigation display hard buttons as described below:
Make sure the battery is connected, then press and hold the three buttons (Menu, Map/Guide,
and Cancel), and keep them pressed for approximately 5 seconds. The display screen will go
directly to the "Select Diagnosis Items" menu shown below.
Touch the Unit Check button, then touch the Aircon button.
7. To cancel the sensor input display mode, press the AUTO button or turn the ignition switch OFF.
The climate control unit has a mode that displays sensor inputs it receives. This mode shows you what the
climate control unit is receiving from each of the sensors, one at a time, and it can help you determine if a
sensor is faulty.
Check these items before using the sensor input display mode
1. Turn the ignition switch ON (II), and check the recirculation door function; press the recirculation
button to switch from FRESH to RECIRC. The air volume and sound should change slightly.
2. Set the temperature control knob to the desired test temperature. When selecting the test temperature,
note these items:
"Lo" temperature setting will default to MAX COOL, VENT, and RECIRC.
"Hi" temperature setting will default to MAX HOT, FLOOR, and FRESH.
58 through 86°F settings will use the automatic climate control logic.
3. Turn the ignition switch OFF.
To run the sensor input display mode, follow these steps
4. Turn the ignition switch OFF.
5. Press and hold both the AUTO and recirculation buttons while starting the engine. Release the
buttons.
6. Turn the ignition switch ON (II). Use the navigation display hard buttons as described below:
Make sure the battery is connected, then press and hold the three buttons (Menu, Map/Guide,
and Cancel), and keep them pressed for approximately 5 seconds. The display screen will go
directly to the "Select Diagnosis Items" menu shown below.
Touch the Unit Check button, then touch the Aircon button.
7. To cancel the sensor input display mode, press the AUTO button or turn the ignition switch OFF.
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