240D fickle A/C compressor - PeachParts Mercedes-Benz Forum

gene2 · #1 08-14-2006, 06:59 AM

O.K. If you are getting power to the clutch at the right time. And the clutch does not kick in... try one more thing, unplug the clutch. With the key OFF. Use a jumper wire and go from battery to clutch, if clutch does not kick in, you know it is the clutch.

Slcom1983 · #2 08-14-2006, 09:09 AM

Quote:

Originally Posted by gene2

O.K. If you are getting power to the clutch at the right time. And the clutch does not kick in... try one more thing, unplug the clutch. With the key OFF. Use a jumper wire and go from battery to clutch, if clutch does not kick in, you know it is the clutch.

I'll give it a try. When I connect a jumper from the battery to the leads on the compressor, do I need to be concerned about polarity? If so, do you remember which spade connector on the compressor is the pos and which is the neg? (left being passenger and right being driver sides).

gene2 · #3 08-14-2006, 09:26 AM

I will check mine later today and post.

gene2 · #4 08-14-2006, 10:47 AM

The brown wire is ground. It is on top if at 3:00 The clutch will kick on either way. Do not know if you should, I am just saying it will.

Slcom1983 · #5 08-14-2006, 08:34 PM

Thanks for all the help...especially Gene2. With the car cut off, I connected wires directly to the compressor and then touched the battery terminals...NOTHING!...not even a click. Does this mean the compressor clutch is bad? It's very odd, but as soon as this test failed I drove up the road and the compressor started working and cooled like a champ. When I got home I turned off the A/C and tried to turn it back on and it wouldn't. This is really a mystery...or is it?

KPMB82 · #6 08-14-2006, 09:30 PM

So you have 12V at the clutch. You need to check the resistance af the clutch coil with an ohm meter. Check with one lead on each of the terminals. I beleave it should be about 4 ohms. Should be good or it would never engage. Next measure the air gap between the front plate and the clutch coil with some feeler gages, your gap should be about .0025 of an inch. If your gap is too large the coil can't pull the plate in to engage the compressor.