My car squeaks sometimes when i turn my ac on. I know its the belt slipping but should i fix it by changing the belt, or could there be something wrong with the compressor.

 

Depends. If it just squeaks, then tighten down the belt and I wouldn't worry too much about putting a new one on. I've tightened down a really worn belt and it was fine. If it's the compressor it will make almost like a grinding or rattling noise. Sometimes if it's a compressor problem when it kicks on it will also make the RPM's stall way down.