Well, this is not exactly a general question, but I am looking for help with the following problem:

1993 Shadow with 150,000 miles. Since the car was almost brand new if the A/C was turned on, the serpentine belt would screech. No one at that time knew what was wrong. Belt is continuously maintained. A couple of months ago, I was trying to investigate the problem more, and took it to a shop. The mechanic tightened the belt and the squeal went away - for a day. I took it back to the shop, and I was told that the compressor of the A/C was bad, and the A/C should not be used and that it could cause belt failure and/or a fire. He insisted even though I explained that the A/C worked fine (it cools and always has for 15 years), and nothing bad had even happened - just the terrible noise from the belt.

Anyway, the sound got worse, and if I turned on the A/C, there would be a smell of burning rubber. I figured the belt was on too tight now. Also, I have noticed very small black particles around the belt area - i'm guessing parts of the serpentine belt are being rubbed off if the A/C is on. I do not use the A/C anymore, and it's really hot outside.

I am wondering if the problem could be simply the belt, a misalignment or something else relatively simple...or if the compressor/clutch of the A/C is bad like the mechanic said. But if the compressor/clutch were bad, would the A/C still be working, blowing cold air? And it has been that way for many, many years.

If anyone has an idea of how I can investigate this problem, please let me know. Thank you.