Problems with wifes Trailblazer vents

My wifes battery went bad a few weeks ago, so I got a new one I put it in and the next morning her ac will not blow out of the dash vents, only the floor and defrost. I thought it was a wierd coincidence and thought it might be the HVAC controls. So I got one from the salvage and swapped them out, still the same problems. I did alot of searching on the web about this problem and 3 other guys on automotiveforums.com had the same problem when they replaced their battery but no one could come up with an solution for the problem. If anyone can help me figure out what caused this to happen or how to fix it I would really appreciate it.

you should check out www.trailvoy.com I have an Envoy and there are a lot of knowledgeable people over there. JIMMY

Thanks man I found exactly what I needed on there

What was it. I had a similar thing happen w/ my envoy. The dealer ended up replacing a relay unit for the hvac controls @ like $450 bucks.