cdaug

I have a 2005 C240 4matic. (203.081).

The car is in excellent condition mechanically and cosmeticaly. The airconditioner has the two zone controls; one for the driver side and one for the passenger side. All system functions are normal including auto mode and manual mode. However, when the system is in the airconditioning mode, cool to cold temperature air emits from the passenger side vents, while warm to neutral temperature air emits from the driver side vents.

I have read the forum posts and kinda figure it may be a "stepper motor" problem. The question is: is it a stepper motor problem and if so, which stepper mottor is the likely culprit? Or, is it another type of problem?

Any help and guidance is appreciated.

I plan to make this repair myself and have no problem removing the dash assembly if the job so requires, although I prefer to keep it simple and not remove any uneccesary panels etc.

Plutoe

Get back to the basics---put on a set of gauges--high should be 210lbs--low 30--what's your settings!!

cdaug

I had my shop check the basics, pressure and temp etc. All good. Cool air flows through the system and out the passenger vents. No so cool air flows from the driver side vents.

samaritrey

What were your readings? Let us be the judge of if they were good or not.
Have you ran the built in stepper motor diagnostics?

cdaug

I don't know the readings and cannot get them without another service appointment. I do read the manuals. (RTFM). I have ordered a service manual. I do not know about the stepper motor built in diagnostics. Is that something I can do? Does it require a special piece of technology or equipment?

samaritrey

Have you read this about the motors?
https://mbworld.org/forums/c-class-w...g-hissing.html

If my memory serves me right (have w211 now) hold down the recirculate and Front defroster until they both start flashing back and forth. If it runs forever you have an issue if not at least that one time the motors went through everywhere they should go.... that said I had my w203 pass and fail it randomly until I found the issue and fixed it.
Using star diagnostics you can do a closer diagnostic.
I had a similar issue with my w203 except mine was no heat out of driver side. Had to mess with something to the right of your right leg when in driver seat. Never did find a problem but did swap a motor with one that was easier to get to behind radio.