560SEL A/C inop

[Tim Mabry]

The a/c quit on my 87 560SEL today. The compessor does not engage. I put gauges on it and it has plenty of freon. I checked and wiggled all the fuses. I jumped the high pressure swich at the drier and the aux fan came on. I also jumped the low switch, but still no compressor engagement. Checked for voltage at the clutch (=0 volts). I tried all button positions including defrost. What should I look at next. Please give detailed instructions including componet location. Thanks. You all have been very helpful in the past.

[MB STARS]

Have you try the a\c relay (right next to fuel pump relay)at fire wall"klima relay"

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MB STARS Master Guild Technician,12 years MB tech
6 years independent shop owner

[Tim Mabry]

I found the a/c relay. Thanks. I think that I am not getting a ground from the control panel. I checked all of the pins on the harness side and this is what I found. 1 ground (31) 2 12v with key on (TD)
3 not used
4 nothing (87Z)
5 12v (15)
6 not used
7 a/c clutch (87)
8 not used
9 not used
10 .8v with key on (KL)
11 not used
12 nothing (T)
Note: relay pins are in ( )
I can get the clutch to engage if jump 12v to pin 7. I think that I should be getting a ground at pin 4 but I'm not. Is this correct or am wrong? Any further info would be appreciated.
Also, are there any CD/ROM service manuals available for my car (W126)?
Thanks again.

I doubt you're having the same problem I had, but what the heck?

The a/c in my 560SEL wouldn't come on, either, until the ignition key was wiggled in the ignition switch. There is some slight play (that I'll probably have to repair one day) in the switch and if the key was not fully turned, the a/c wouldn't come on -- no fan, no nothing. Dealer showed me what was wrong and said it's a common problem. Switch can be just slightly off position and the engine will continue to run but the a/c won't go on. I would have lost money on that bet.


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Al Spalmacin
1989 560SEL
1989 190E 2.6

yes there is a cd for your 126 you can get it at the closes MB dealer to you. on monday I will get my 126 cd and give you the pin location for the push button control unit and you can go from there. but I always advise people take there Mercedes to someone who knows the car.