535i A/C Compressor question

[Newbie535i]

I have looked in the forum, online and my Haynes Repair Manual and have not found an answer to my question. If I overlooked it, my apologies.

Last week I spent 2243.94 on a new heater core, expansion valve, evaporator core, drier, pipes, o-rings and retrofit kit to R-134. I figured that since my dashboard was going to be dismantled, I ought to have the heater core replaced as well.

My question is when the a/c is running, everything sounds fine. When the engine is shut off, I hear a squeaking sound coming from the compressor. The compressor starts to spin in reverse (clockwise). My mechanic explained it as the compressor was reversing course to equalize the high and low end pressuers and then it would stop spinning.I asked him if this was a bearing, as it sounded like metal on metal. He assured me if it was metal on metal the noise would continue when the compressor was running, which it does not. I asked if there was a valve that was supposed to equalize high and low pressures within the compressor itself. He said the valves in the compressor had nothing to do with that. I asked if the compressor had the correct amount of lubrication, which he said it did, but to be assuage my concerns added a small amount of synthetic ester. He put the pressure gauges on to show that it has holding the charge.

I did not have this problem prior to having all this work done. Is my compressor going? Am I asking the right questions?

Also I have several pictures of the dismantled interior and engine compartment for any interested.

Thank you in advance for your assistance.

[gale]

I'm guessing the a/c clutch is dragging. Perhaps the pulley was bumped during the conversion & has a wide and narrow gap when it freewheels. Most a/c clutches have a means to adjust the gap with shims. Maybe have the shop take a look at it & tweak it. The compressor running in reverse momentarily is normal as the mechanic explained.

more info:

http://www.bimmer.info/forum/showpos...27&postcount=7

[shogun]

I have looked in the forum, online and my Haynes Repair Manual and have not found an answer to my question. If I overlooked it, my apologies.

No, you cannot have overlooked anything, because the Haynes is not worth the money.
Buy a Bentley Repair Manual, that really helps, it is the socalled "bible" of the E34 driver.

Pics of the repairs are always welcome here, as it is good to study and helpful for many of us for their own work in progress.
Use imageshack or pfoto-bucket or whatever is free to post m,any pics. For those with slow PC-connections it is better that you just link the pics.