1994 e320 A/C trouble please help!!! - PeachParts Mercedes-Benz Forum

usman21 · #1 07-09-2007, 09:22 PM

1. My A/C used to work normal and one day i was driving on the highway it quit on me.
2. the next day it worked on for 15 seconds and the compressor would disengage. it would every time i turn off and turn on the car.

3.now the compressor tries to turn but works only 1 second.

I dont know what to check please help all you A/C guru's out there.
i do know that i have freon.

david s poole · #2 07-09-2007, 10:46 PM

your compr clutch is powered by the mas relay.this is the place to start.identify the two large pins #15 and #87.find some copper wire and join those two pins together and plug in the relay.this should make compressor run.now check all the easy stuff like does it really have enough freon.

deanyel · #3 07-09-2007, 11:47 PM

It's fairly common to have a bad connection on the compressor speed sensor at the back of the compressor. The wire is too short, the engine sinks a bit over time and the connection snaps. The compressor speed signal is compared to the engine RPM and the two numbers must be close for the AC to operate. If it's not getting the compressor speed signal it can't compare the two and the compressor is blocked.

usman21 · #4 07-10-2007, 09:12 PM

Quote:

Originally Posted by david s poole

your compr clutch is powered by the mas relay.this is the place to start.identify the two large pins #15 and #87.find some copper wire and join those two pins together and plug in the relay.this should make compressor run.now check all the easy stuff like does it really have enough freon.

hi david the compressor turns on when i jump pin # 15 and 87 and yes i have freon because A/C blows cold. what would that indicate do have bad relay? or something else i need to look for plz help.

saumil · #5 07-10-2007, 09:42 PM

If your car's Klima relay is similar to that in 87, 260E, then check this post, I have a systematic way to check the compressor cut-off.

http://www.peachparts.com/shopforu...=158591&page=5

david s poole · #6 07-11-2007, 10:27 AM

it means that this is a control circuit problem.there is a slight poss that the compressor clutch is drawing too much power and has blown the mas relay.you need to find an amp meter and see how many amps being drawn by clutch[should be btwn 5-7] if that is good then we have the speed sensor on the compressor[gk+ and gk-] you can identify these pin sockets [where mas plugs in] and measure with acvoltmeter.notice ac not dc.and then there is the temp sensor in the water jacket that is supposed to cut the comp off during an o/heat and this could have gone bad.not sure of pin designation but will have letter t in it.if measured at mas socket and is a ground then this is problem should be open circuit.try these and see what's going on.

James L · #7 07-11-2007, 04:30 PM

david is right on, the service cd has a good compressor cut off troubleshooting section, (I am following it for my 1993 w124).

usman21 · #8 07-17-2007, 12:31 PM

does anyone link for the systematic? or copy of it? and location where the mass socket location is?

saumil · #9 07-17-2007, 05:09 PM

Do you mean the socket for the compressor cut-off relay (Klima) ? I am not familiar with your car, but on my 87, 260E, it is behind the plastic cover that goes behind the battery. There are two black relays, the one in front is the fuel pump relay and the one behind it is the compressor cut-off relay. If your relays are MB original, the climate control relay could say Klima.