My alternator belt tensioner failed a little while ago and when it did for some reason the accessory belt was squeaking around the ac compressor pulley. I replaced the alternator belt tensioner but every time I put the heat on, the belt squeaks around the ac pulley. Does this mean I need a new ac compressor? or just the pulley? I am a newbie at this but I am be capable of doing it myself, I just can't diagnose the problem. HELP!