I bought a used 2004 chevy trailblazer LT 4.2L with 4WD just the other day. Everythung seems to be worming just fine, expect that it has been on the cool side and I havent needed to use the a/c until today. I know the sales person at the place i got the the trailbrazer from and he always drives his vehicles home a few times to make sure there is no issues. He said the a/c was working fine when he was working fine when he was driving it home and back to work. The day before I bought it he said the battery light came on and ge had it tested. He replaced the battery and the battery light went away. However, when i went to use the a/c today i had cold air coming out of the driver side vents, but the passenger side and the rear vents were all blowing hot air. I already pulled and checked the little 10 amp fuse for the a/c and it is good. Any thoughts on what could possible be wrong with it that I could cgeck or have checked before i take it to a mechanic?