Dear Listers:

Car: 1994 MB C280

I have put in a tested newly rebuilt compressor, new belt and new drier. I have gone to a professional shop to have the system evacuated, tested and filled. It is holding the perfect amount of coolant pressure wise. The compressor still does not kick on. There is no current going to the compressor at all.

My trouble codes are, 20 (Evap. Temp Sensor Short circuit 3), 30 (Refrigerant Pressure Sensor short circut 3), one , and 66 (auxillary fan stage 1 short circuit).

An exact list of HVAC W202 codes can be found here (half way down thread): http://www.club202.com/forums/showthread.php?s=&threadid=7642&perpage=15&highlight=air%20codes&pagenumber=1

Could these two sensors be bad? Also, the fans kick on thermostatically but not when the A/C is put on.

Thank you in advance for your suggestions.

Michael

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Michael
Southern California/Santa Monica
1986 MB 190D 2.5, 5 Speed Black and Palomino "Mordechai"
1985 Porsche 928S (32V), 5 Speed
1980 Porsche 928 (16V), 5 Speed

Bump.

I am having a massive headache and expense with my AC system. Maybe someone can help me. My compressor will not turn on. Not even for a second still.

In addition to the above, I have replaced my Refrig. Sensor Switch. Today, I had it retested, re-evacuated, refilled.

Observations: When I pull the sensor wires, the high speed fans (both) kick on. Also, I tested the three pin wires that connect to the pressure switch, two are not live and one has just enough juice to light the test light but not very strongly (first pin on left when the lock is on top).

Please help.

Thanks. Michael

__________________
Michael
Southern California/Santa Monica
1986 MB 190D 2.5, 5 Speed Black and Palomino "Mordechai"
1985 Porsche 928S (32V), 5 Speed
1980 Porsche 928 (16V), 5 Speed

The fans will run based on refrigerant temperature (and possibly pressure -- I'm not sure of your car). If the compressor isn't running, the fans won't start solely because you selected AC.

I am not sure of your car, but the evaporator temperature sensor is a common problem on the W210. Does your car offer any sort of current-sensor value readout?

Yes, I ran the codes and one of them came up as the pressure sensor and one came up as the evap temp sensor. However, since I cleared them the other day, they have not returned. The more I read on the subject, I worry that the problem is the a/c control unit. However, I want to be sure to try everything else before I take on that sort of expense.

Could a faulty evap temp sensor cause no current at the compressor?

Thanks for your help.

Michael

__________________
Michael
Southern California/Santa Monica
1986 MB 190D 2.5, 5 Speed Black and Palomino "Mordechai"
1985 Porsche 928S (32V), 5 Speed
1980 Porsche 928 (16V), 5 Speed

Absolutely.

Thanks Matt. I will pick one up at the dealer this week? Does anyone have any pictures as to where to look for the sensor. Is it accessible without removing the dash? Thanks. Michael

__________________
Michael
Southern California/Santa Monica
1986 MB 190D 2.5, 5 Speed Black and Palomino "Mordechai"
1985 Porsche 928S (32V), 5 Speed
1980 Porsche 928 (16V), 5 Speed