AC Contols intermittant
06-01-2017, 03:13 PM
#1
Member
Thread Starter
AC Contols intermittant
So, finally got the CPS working and the car is reliable again, and the AC/HEAT started going crazy.
Start the motor and something under the dash makes a mechanical popping sound for about 30 seconds. It has done this for a few months, but no other symptoms.
Now it does it, but the AC goes full speed, high fan on the engine as well, for a few seconds, then everything stops. The controls are lit, and react to button pushing, but no AC, no fan, no heat, nothing.
The car is not overheating at all, so no fan issues, but WTF? I did notice that I could firmly tap the controls, and at first that helped, but now it does nothing.
Bad controller?
Start the motor and something under the dash makes a mechanical popping sound for about 30 seconds. It has done this for a few months, but no other symptoms.
Now it does it, but the AC goes full speed, high fan on the engine as well, for a few seconds, then everything stops. The controls are lit, and react to button pushing, but no AC, no fan, no heat, nothing.
The car is not overheating at all, so no fan issues, but WTF? I did notice that I could firmly tap the controls, and at first that helped, but now it does nothing.
Bad controller?
06-01-2017, 08:22 PM
#2
MBworld Guru
The popping sound is probably a broken duct control arm or servo. The parts are not expensive, but depending on which on it is, it can be a major job (i.e. remove entire dash, evaporator, heater core, etc.).
Do try the ACC reset though: With the engine running, simultaneously press and hold the RECIRC and FRONT DEFOG buttons until their indicator light begin to flash. This will continue for about 30 seconds until all dampers and functions have been tested. If it does not stop, then there is a fault and you'll need a proper diagnostic (pulling codes from the ACC with SDS).
Do try the ACC reset though: With the engine running, simultaneously press and hold the RECIRC and FRONT DEFOG buttons until their indicator light begin to flash. This will continue for about 30 seconds until all dampers and functions have been tested. If it does not stop, then there is a fault and you'll need a proper diagnostic (pulling codes from the ACC with SDS).
06-06-2017, 11:36 PM
#4
Member
Thread Starter
Ok, so I took apart the control panel, cleaned the contacts, cleaned the sensor, and reinstalled it. It appears to be working, for now.
Here are the codes I drew before I did anything.
Here are the codes I drew before I did anything.
06-07-2017, 09:50 PM
#5
MBworld Guru
Just in case you still have an issue with the humidity sensor, it is in the overhead control panel and has a small fan to draw air across its thermistor. You might try cleaning it with compressed air.
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JimVonBaden (06-07-2017)
06-20-2017, 06:36 PM
#6
Member
Thread Starter
Worked for 6 days, then same problem. Figuring that would be the case I ordered a replacement from E-Bay. I received it today and installed. So far, so good.
I also cleaned the humidity sensor. Thanks Rudeney!
I also cleaned the humidity sensor. Thanks Rudeney!
