In Reply to: Repost: a/c compressor noise posted by Rodney Lyn on August 27, 2001 at 21:21:42:
I had a similar noise in my '92 a/c. What was causing my noise was a slight overcharge of freon which caused higher pressures in the system. These higher head pressures (pressures at the compressor) would cause the output line to hammer or vibrate, particulary when decelerating. Also, a worn compressor will exhibit these symptoms, and higer head pressures will exagerate the noise. I am guessing your system could be overcharged.
Run the car at idle with the hood open an a/c on. Have someone rev motor up to about 2k rpm & then let off gas to see if it will hammer.
Since yours is a 94, it should have R-134a in it, Has your system been serviced lately? Could be overcharge and/or topff off with just R-134a and no oil. The oil leaks out with the gas.
You need to check the pressure with a/c gauges or have a shop check it out.
Advice is free, no warranty implied, use caution etc.
The compressor on my 94 530i has been noisy since I got the car 2 months ago. It was whining ... had the belt and tensioner checked and both were fine. This past weekend I got caught in some thick traffic and after idling in traffic for say 3-5 minutes the compressor starting making a very loud and deep hum. As soon as I turned off the a/c the noise vanished ... so I know its the compressor. The a/c is ice cold at all times. I realize the two problems could be two different issues but does anyone have any ideas about what the problems is? Do these compressors take oil/lubricant?