cowans

Well, with the 'search' being disabled, I'm finding it hard to see if anyone has had the problem that my wife is complaining about... She says that recently there is cold air blowing at the feet all the time, even with the temperature turned up to 28C degrees (85>90*F). The air will turn to hot if she cranks the temperature up to 32 degrees (24 use to be a comfortable temperature). Any thoughts/suggestions???
Sandy

imjd

Bad cabin temp sensor?

If the system is working normally, this is what should happen:
If you turn the temperature setting up to the maximum, you get hot air no matter what the interior temperature.
If you turn it to the minimum, you get cold air no matter the interior temp.
At all setpoints between minimum and maximum, the controller is supposed to modulate the air temperature and air flow (i.e. fan speed) to maintain the setpoint temperature in the cabin, more or less. At the maximum and minimum setpoints, the fan speed will still be modulated but the air temperature will be full hot or full cold.

It sounds to me like you get the behavior that when the setpoint is cranked up to max, you get heat. You probably haven't tested the minimum setpoint, and indeed that would be difficult to do until the weather turns cold. However, going on what you do have, it suggests (but does not prove) that the controller may be working OK. Therefore probably the first place to look would be the cabin temperature sensor.

There is a self-test procedure that may help to diagnose what the problem really is. Start the car and within 10 sec. press and hold the "off" button on the a/c panel. Hold it until you see all the display segments light up, then you can release it.

Turn the temp **** to the right one click. This starts the self test. After a while (30 sec or so) you should see a result code. "20" means all the sensors checked out OK.

other
code: means problem with:
21: ambient temp sensor
22: in-vehicle (i.e. cabin temp) sensor
24: intake sensor (misleadingly named, it is actually at the output of the evaporator)
25: sunload sensor (it's normal to get this "error" code if the test is conducted under any illumination except outside during daylight.)
26: air mix door positioner

But, note that if more than one temperature sensor shows bad, you should probably begin to suspect the controller.

After this you can turn the temp **** one more click to the right. This starts a test in which the airflow doors will be moved and this test takes a little longer. Normal result is code 30.

other
code: means problem with:
31~36: mode door (the door that sends the air to the panel vents, footwell vents, or defroster vents
37~39: intake door (switches between fresh and recirculated intake air)

One more click of the temp **** gets you into the 4x set of tests. Press the "def" button to cycle through 41~46. Each code represents a different combination of airflow, air temperature and vents that you can verify.
41: panel vents, intake -> recirc, cold air, blower medium-low, compressor on
42: panel+floor, recirc, cold, medium-high, on
43: panel+floor, mixed fresh/recirc, hot, medium, off
44: floor, 100% fresh, hot, medium, off
45: floor+def, fresh, hot, medium, on
46: 100% def, fresh, hot, high, on


One more click of the temp **** and you are in test mode 51. This might be quite useful to you. Use the "def" button to display the temperature measured by each of the three sensors:
first press: display ambient temp
second press: display cabin temp
third press: display temp of air exiting evaporator

You can verify the ambient and cabin temperatures readily and if you have a bad temp sensor, it will show up here. (if it didn't already trigger a code in mode 2x.) The evaporator exit temp is a little more difficult to verify but presumably you could measure the discharge air at the panel vents in mode 41 and compare it with the reading in this test.

From mode 5x, if you press the fan-increase rocker switch, it toggles the temperature trimmer mode. In this mode, twist the temp **** to select an offset (positive or negative) that will be added to the displayed temperature to produce the "real" control setpoint. This has nothing to do with diagnostics but it's your prize for reading this far.

You can move back and forth through the different test modes by twisting the temp **** left or right. You exit the self-test mode by pressing the "auto" button or simply by turning off the ignition key.

Hope this helps to isolate the problem. If it does turn out to be the cabin temp sensor, it is located behind the small grille in the plastic trim just to the right of the steering column. You are on your own as far as removing the trim.

cowans

WOW! Thanks IMJD. Great informative writeup! I went out this am and went through all the diagnostics... came up clean! 1last note, when adjusting temp, heat will only be dispersed at 32C(temp **** adjusted to max heat), any other setting, ex: 24C cool air will be blown out! All the selftests run clean, with no improper codes...
Your writeup was great!
thanks, Sandy

Maximadmoiselle

iTrader: (1)

So I'm not the only one... I have the exact same problem if you want to call it that. I did the diagnostic procedure as per the ESM and it was the intake door that turned out to be the problem. Took it to the dealer and was told there was nothing wrong with the intake door, but that I had to buy a new compressor ($700+......). Took it to another dealer and was told that my compressor is perfectly fine.. that's how far I've gotten so far

cowans

Maxi, thanks for your response. I agree with your finding of the intake door. I can't believe any mechanic(especially a dealer) would have said the compressor was the problem. DUH! the temp is freezing, unless it's dialed up to max heat!
Sandy

Maximadmoiselle

iTrader: (1)

What I don't understand from your posts if whether the fan speed changes (1-4 on the fan light) as you keep turning the ****. And even if it does, does it feel like the air it's blowing has the same temperature at any setting before 32C? Is it that only your fan speed changes, not the temperature of the air flow? As for my case, I have to do the diagnosis again, it's just not cold enough outside yet. Good luck finding what the problem is.

cowans

Ok, I thought I'd better update this.... The problem was the evap air sensor. I was going to replace it myself until someone told me I would have to 'fight' with the evaporator to get at the sensor. So, off to the dealer to regurgitate my 134A, pull the evaporator and replace the evap sensor... the wife has got heat again! LOL!
Thanks to all that responded....
Sandy