I got the rear drivers side tail light replaced the other day, did it my self with my dads help. two days later, my battery light comes on and my a/c unit wont work at all, not even heat or fan control. I have been told i may have shortcircuited something but i am not sure. I live in dallas texas and even now the heat is unbearable for black leather seats in cars lol

 

check your alternator fuse under your hood. right next to your battery, should be a mega 120 fuse. if that doesnt work it possibly your ground cable or alternator.

 

Man I hate that light...mine popped up last month. My power steering pump was leaking onto my alternator and shorted it out. Also might want to check that out as well.