Help! my 300D AC is acting crazy. it is 100 degrees outside and I am running my AC is running fine, then all of the sudden, the vents start blowing HOT air!! The compressor is running but the heater valve is allowing hot water to go to the heater coil. I checked the voltage to the valve and it was 6 volts. I jumped 12 volts to the valve, it closed, and the AC blew cold again. Does anyone know what the problem is???? Please help. DB

Look at my message "W202 C240 A/C failure due to faulty ext. temp. probe" that I posted ont the 6th of july. Seems similar, no?

Richard.

We must know what year model or series this car is. There are several different 300D's and it's impossible for us to read your mind.

If it's a late 123, 81 to 85, the problem is most likely the monovalve.

If it's a 124 car, the problem is most likely the pushbutton control unit.

Let us know what model and we will give you more details to help you properly troubleshoot before wasting money on unneeded parts.

Have a nice day,

Sorry, it is a 1983 300D.