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?