1988 300E M103 75K miles

I recently replaced all the O rings, receiver-drier, expansion valve and added R134 and the proper amount of R134 compatable oil. My high and low side pressures were good and I was getting 40F at the vents on an 80F day. All was well until today, compressor clutch stopped engaging and when I tried to jump it (via the pressure switch) nothing. Can I send power directly to the compressor to see if it will engage? The connection has three wires to it.

Best test is at the Klima relay, behind the battery.

There are several good write-ups on testing at the "Klima relay" on this forum.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

yes

__________________
Jim

Thanks for all the good info. I will jump the Klima, and/or jump the compressor and check the clutch airgap and get back to you guys tomorrow.

Did you recheck charge to ensure it didn't leak out overnight after you drove the car?

__________________
2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Yes, it's been holding the charge for over 1 week so far. I can only check static with the compressor not working.

My compressor is bad. The clutch wouldn't engage after I jumped it. . I'm going to get a rebuilt one to replace it and hopefully have cold air again.

If it's only a bad clutch, you can replace only the clutch. It's a PITA to work on even with the radiator out. You might buy some working room if you detach the compressor and tilt the clutch downward.

Sixto
87 300D