#$%*&$ Air Conditioning W210
 

Reaching the end of my ropes.. I had the RD, Condenser, and compressor replaced back in May. Yesterday while running some errands I noticed all of a sudden the car was getting warmer, felt the humid air. I got home and saw that the compressor was still engaged. I ran through the diagnostics and didnt get any errors. I also hooked up a can of R134 I had and the meter went into the red DANGER ZONE, I was definately hooked up to the low pressure side. I am stumped. before I take it in, any thoughts.

Was the low pressure hose cold? was the drier VERY hot?

IF so possibly the heater valve was in the open position.

MB Doc,

Thanks for the reply. I was getting abient air temp through the vents. It was like I turned of the AC compressor even though the clutch was still engaging and disengaging when I hit the EC button. What concerned me the most was the low pressure side had such a high pressure. I am wondering if the Evap Valve failed?? Or the new (rebuilt) compressor had a catastrophic failure.

Are you sure your compressor clutch is engaged ? There seems to be no suction by the compressor, almost like it is not operating. It could be that your expansion valve is stuck open. If you hose the condensor with water, does the low side pressure go down ? If it does, then you may be overcharged. Can you check the high side pressure ?

Bad compressors make noise... you should know it.

With R134a, I would be careful with just adding freon arbitrarly- the high side can climb and kill that compressor. Is the fan coming on? What are the pressures and temps.

The best way to verify a bad heater valve would be easy to check. I would disconnect the compressor, set it to max cool and measure the vent temp, it should match ambient pretty quick. If it hot, then replace the heater valve as they are not expensive.

Michael

Thanks for the replies.


I did verify that the compressor is engaging, I can see the clutch and its either spinning or not depending if I put it in EC mode, and can hear it engage. I am leaning toward the evap valve also, thats the only item (other than the evaporator) that I havent replaced. I found an Indy in York that advertises in our MBCA Keystone Section mailer and will be dropping it off on Wed eve.. I am going to try and test the AUX fans tomorrow, I drove the car today, and noticed that by engaging the AC there wasnt even the slightest drag on the motor, its like the compressor is freewheeling inside, the clutch enguages but has no resistence.

Your still not diagnosising the problem,


What are the pressures and temps for the system. If the TXV fails closed, then you'd be pulling a vacuum on the low side. If it was wide open, your high side pressure would be way low for the temp.

I'd let the Indy look at it instead of just replacing parts.

Mine is acting strange and we're going to evacuate and re-charge the system. It either has some air (bad bad thing I'm told) or it has some debris which hopefully found a home in the dryer/filter.


Michael