We first noticed that as long as the A/C was on and you accelerated, there would be a rattling under the hood on the passenger side. It kept getting worse and louder. Finally, one day, the wife complained that the A/C wasn't putting out cold air. First thing I did was get underneath and saw that the belt was completely gone. I replaced the belt and the tensioner in case that was what caused it to break. Meanwhile, the noise was getting worse. I finally took it to our mechanic. He said that he had received a bulletin from GM about it. For some reason, the A/C oil seems to "pool" in the compressor and really causes that belt to flop and eventually the compressor fails. He is now installing a new engineered compressor from GM with some kind of filter they recommend. This with a new dryer is costing us a little over $1,000. 136,000 miles is pretty low for an A/C compressor to go bad. My 68 Impala is still using the old style huge compressor and is still going strong. I feel like GM goofed and they are the ones who should pay this big repair bill.