W203 Airconditioning Problem

[sv4]

I have a problem with the AC in my C230K that has left my regular independent mechanic stumped. On first start in the morning ( or after leaving the car parked for 5-6 hours ), the AC will only start blowing cold air after 6-10 minutes although the fan starts immediately. Previously, the cool air would come on fairly quickly, at least within a minute of turning on the AC. Once the cool air comes on, though, the AC performs very well. The AC would then also blow cool air almost immediately after short periods of stopping/restarting the car.

Full check on the airconditioning system revealed no leaks and refrigerant remains fully charged. Winstar diagnostics revealed a faulty evaporator temperature sensor which was promptly replaced. However,while further diagnostics revealed no more faults, the proble, persists. I would appreciate any suggestions, thanks.

 

[eric242340]

I have a problem with the AC in my C230K that has left my regular independent mechanic stumped. On first start in the morning ( or after leaving the car parked for 5-6 hours ), the AC will only start blowing cold air after 6-10 minutes although the fan starts immediately. Previously, the cool air would come on fairly quickly, at least within a minute of turning on the AC. Once the cool air comes on, though, the AC performs very well. The AC would then also blow cool air almost immediately after short periods of stopping/restarting the car.

Full check on the airconditioning system revealed no leaks and refrigerant remains fully charged. Winstar diagnostics revealed a faulty evaporator temperature sensor which was promptly replaced. However,while further diagnostics revealed no more faults, the proble, persists. I would appreciate any suggestions, thanks.

Ask your indie to check the control unit, on the front of this unit you should find two little vents and they tend to clog up with dust. Had this problem on many Benz models and I havent worked out why a little dust can cause this but it appears to me that if the vents block the control unit cannot check the in car ambient temperature. Also Winstar is fairly accurate with aircon and if there are no fault codes it points back to the control unit/wiring. Did they have the control unit out?

 

[sv4]

Thanks, Eric. Will have a look when I get home later. The indie did not have the control unit out. However, I did ask him about the possibility and he did not think so.

 

[sv4]

Looks like it wasn't the control unit. I noticed that the compressor wasn't engaging at AC startup, until the engine had warmed up sufficiently. When the engine cools down, the problem recurs. On another forum, a faulty expansion valve was suggested, haven't had the time to take the car in again. Any other ideas, anybody?