W203 A/C problem
 

Hello A/C gurus

New 2002 W203 C-Class Sedan, but same scenario as Mr. Raygun17

AC = Hot air output when hot outside (80-90 degrees actual air temp), and idling/sitting.
AC = Works fine when in shade, running on freeway etc.
AC after running and then parking in the sun, takes forever to come back into cool air mode.

There is a A/C diagnostic mode one can enter into on the front of unit, all looks OK (to me) except the register for "Outside Air Temp", It reads in the 69-84 range when OK and gets into the 120-165 range when the AC is blowing hot air.

Do you think the Recirc Flap is likely? where is it actually located and how to easily test it?

FYI Excel spreadsheet of Diagnostic Mode, attached

The vehicle is under warranty. Why are you not just taking to the dealer??

Warranty
 

Warranty: Yes

But I prefer to have a good idea before I take it in.

The 203's have eletric stepper motors on the flaps, blend dorrs and no monovalves on the heater cores.


The system uses inputs from the interior temp sensor, sun sensor, temp dial setting, evap temp sensors,heater core temp sensors and refridgerant pressure to establish the compressor "wobble plate" duty cycle.


Odds are you have either a bad evap temp sensor, pressure sensor or ambient sensor causing this. However I seem to remember something about the AAC control units on some models.


Joe

Thx Joe
 

Did you look at the attached file for your diagnosis?
I think the data I attached might shed some light.


Agree control head unit is likely candidate, others have posted probs solved by new control unit, not the same symptoms though.