Does it squeak all the time or only when you start it? If its just at start check the belt tension. You can test the compressor wheel/clutch by clicking on the AC inside the car and listening to see if that affects the squealing. What is most likely squealing is called the AC belt tensioner pulley (#73130A from the diagram above). You can pick up a replacement one at your auto parts store for pretty cheap, i got mine for 30. Install took me like 20 mins.