Compressor Fried Klima?
 

Hi,
The AC in my 86 16V suddenly stopped working. The compressor will not engage. I opened the Klima relay and found a burn mark on one of the copper strips on the PCB which connects pins 5 and 7 through the relay to provide power to the compressor clutch. I soldered a wire to by pass the burned strip and the compressor engaged for about 10 seconds and cut out again. I opened the Klima relay again and found the same problem. I did this twice with the same results. Can a faulty clutch burn up the Klima relay? The compressor turns freely when I turn it by hand.
Thanks!

Sure can, got one in the shop at the moment on a 88 300TE.

The clutch coil should have 3-4 ohms of resistance and thus draw 3-4 amps. The one in quesion has less than 1 ohm and burns a 16amp fuse instantly with the Klima by-passed.

Thanks Steve. How do I measure coil resistance? There are three pins on the compressor (two are for the speed comparator circuit and one is for the 12V from the Klima relay( power in). I assume I should I take it between the compressor power in pin and ground with the engine off....is this correct?
Thanks again

Yes.

Mine also measured less than 1 ohm (approx .5). Time to order a new compressor with clutch (or just the clutch).
Thanks again Steve!

I'm replacing the clutch assembly with a MB rebuilt. List price is about 150. We will do it on the car as the TE has the rear hydraulic lines complicating compressor removal. Besides if we don't remove the compressor the system can be left alone.

Do you reccommend I replace the whole compressor/clutch assembly or just the clutch. The compressor has atleast 120,000 miles on it. How susceptible is my compressor to the "black death" caused by the teflon breaking down and contaminating the entire system? Am I over reacting...should I just replace the clutch and call it fixed or shall I go ahead and replace the compressor and drier as a preventive measure?

The common use of such logic says that if the compressor clutch is bad maybe I should replace the whole car. With interest rates and rebates, it may be possible to drive a car and never pay for a repair.

I'm too old for such logic. Good compressors don't come with a clutch so there is no reason to replace what hasn't failed.

Black death is most common on rebuilt Nippondenso compressors. one of the worse things that can happen to a good AC is to replace the compressor with a POS rebuilt for such logic or cause it leaks and wind up installing a rebuilt can of black death disguised as a cheap rebuilt.

I agree...why replace a perfectly good compressor. Just bought my clutch from the dealer today. Funny how it's cheaper at the dealer (with my MB discount) than the local auto parts stores. I'll install it this weekend so I can swing by and return the core sometime next week. Thanks for the insight and all the help.