QuestionI can not adjust temperature or fan speed with my climate control unit. Since I can’t get the temperature to adjust I only have cold air either on a max AC setting or very reduced flow by manually changing the where the air is circulated to (dash vents, floor vents).
I have replaced this control unit that is located within the middle console. Did not change the problem. I have been told that it may be the Body Control Module which apparently also contains the odometer mileage. I have also been told that it may be the Temperature Control Module. I have had offers from online parts places to ship a BCM ranging anywhere from $25 to $175.
Trying to figure this out without incurring another $1000 bill at the dealership. Am worried about changing the odometer mileage with an old unit. Do not want problems when I go to sell in the next couple of years.
How do I proceed?
AnswerHi Dennis,
I am pleased that you tried the test and found a code 26 that detected a problem with the in-car temp sensor. The most recent manual I have is for the '94 LH cars which it similar to yours, I believe. On that model the sensor and a small fan are located in the dash behind the nameplate. You may hear the fan running by merely opening a front door and listening. It runs for 5 minutes even if you don't start the engine. It has four wires: a 12v supply that is there all the time, an actuator wire that grounds to turn of the fan, a sensor ground, and a sensor signal. If the sensor opens or grounds the system is supposed to return to manual mode and your manual may tell you how to operate the system when that happens (the display turns blank at that point).
You can test the fan by putting a piece of tissue in front of the intake (may be at the nameplate). There are a couple of foam seals that need to be effective, but I am not clear as to how to inspect them. Most likely the sensor is bad. There is a description of how to remove it:
The right end panel of the dash is removed (appears to be held on by clips, lever it off with the tip of a screwdriver).
The trim bezel that runs from the right end of the dash toward the midline, that includes the name plate, is held in place by a screw at its right end and friction. Once removed you will see the sensor assembly.
You might be able to get a used one from a wrecking yard if the cost at a dealer is too high.
The four wire plug can be verified but I suspect that between '94 and '99 the pin assigments changed at the body computer. Most likely either the aspirator blower is not working or the temp sensor is not working any longer.
Let me know if you have more questions. Thanks for the positive evaluation.
Roland
Hi Dennis,
There is a self-diagnostic capability built in to the Climate control unit. Turn on the engine and let it idle. Set the temp to 75 degrees. Push in and hold simultaneously the floor, defrost/floor, and windshield defrost buttons until the display blinks, then release the buttons. Some two digit numbers should then come up on the display which are the fault codes. Go to www.allpar.com/fix/codes_climate
for a translator of the codes. Write me back and I may be able to tell you specifically what to do to respond to the codes.
I would not throw any more money at the problem by buying expensive parts. You need to get the diagnostics information to do this repair intelligently and economically.
If you need to change the BCM the mileage can be reset by a dealer using the diagnostic readout box. But don't jump to the conclusion that the BCM has anything to do with your problem.
Roland
