compressor clutch not engaging

[RDSTULL]

i have a 1997 300D that the compressor clutch is not engaging. it's full of 134 but blows warm air. is there a cycling switch or something that could be the problem? it was working last fall before i stored it.

[Matt L]

Is that a E300, or is the year wrong? If the former, extract the current values from N22.

[RDSTULL]

yes it is a 1997 E 300. the name plates were deleted on this one. i'll get it right sooner than later i hope!

[KCM]

There definitely should be a low pressure switch, usually on the receiver/dryer. You can jump across the terminals to see if the compressor will kick on, but only as a test and not permanently. Are you sure it is full of R-134? If the level gets too low, the switch will prevent the compressor from turning on as a safety precaution.

[Matt L]

Originally Posted by KCM

There definitely should be a low pressure switch, usually on the receiver/dryer. You can jump across the terminals to see if the compressor will kick on, but only as a test and not permanently. Are you sure it is full of R-134? If the level gets too low, the switch will prevent the compressor from turning on as a safety precaution.

There most definitely is not a low-pressure switch on the receiver/dryer.

Edited to add: Do not, under any circumstances, follow the instructions above. This car is different from what KCM has seen in the past. If you short any terminals on the sending units on the receiver/dryer, you are likely to damage some very expensive parts.

[RDSTULL]

thanks matt, it is full of 134 and i think i'm going to try what i believe to be a pressure switch on a line up front near the compressor. a person that i work with used to work for MB in ann arbor and is also giving me info.
thanks again.

[Matt L]

Check the current sensor values in the pushbutton unit N22. A search here should bring up some instructions.