So my dad owns a 2000-2001 Chevy tahoe, and he seems to have this curse with A/C's because every car he has owned the ac has had at least one or more problems. but anyways... A few weeks back he had to drive it to a nearby town to pick something up, and as we were leaving the car made a horrible like metal screeching and there was a loss of power, and every time he accelerated it made the noise... so this night after weeks of it doing this I decided to get to the bottom of it. I cranked the car and revved the engine, When I got past around 2000 RPM it made the noise, I turned the AC off and revved it up again, no noise... So we went and drove around and revved the car up to about 5000 RPM (The v8 sound awesome that high) without the AC compressor on. No noise. turned it on again, revved loud screeching noise. What could this be? He has had a compressor go out before, but its not like a extremely loud noise, but its noticeable and there is a power loss when it does that. Could it be as simple as the pulley for the belt going out or something much worse. I'd like to get a general idea, because he is probably going to take it into the shop in a few days.. This is going to be my car in 2 years, and I hope it doesn't steadily go down hill.