Does the ac run on just that belt or do other acc. also run on that belt? Is the "Check Engine" light on? I heard that Advance Auto has a diag. machine they can plug into the diag. port to see why the check engine light is on. Funny thing my check engine light came on 2 days ago and I was at Advance Auto today and forgot to ask lol. Could it be a short somewhere? When was the last tune up performed on the vehicle? Could it be the alternator? So many different things. I would have Discount Auto Parts bring out their battery/charging system test machine out. I believe it tells you if its your battery/alternator/starter. It could be so many things.