On a 2003 sierra the ac blows cold on driver and hot on passenger side What would be causing this?

Answer 1

I had it happen on my 2006 with climate control when it was new and under warranty. There are two electric actuator motors in your hvac system.. which in my case necessitated removal of the two front seats, the center console, the entire dash panel and pretty much everything in the dash, to get at. The one on the right is particularly buried, and the one on the left, didn't require much time or effort to fix at all. My problem was intermittent.. if you switched driver's side to hot, and the passenger's to cool, and then adjusted one or the other, something wouldn't work right and I had heat on one side and cold on the other until I cycled my key once or twice.. and then it would all of a sudden adjust.. and stay stuck in the new position it was, even if you adjusted it again. So the bottom line is, these actuator "doors" are actually electric motor controlled "doors" inside your dash, that, if faulty, will give you the symptoms that you're describing. I assume that particular design hadn't changed much from 03 to 06.. and I'd imagine would be very similar whether you're using the electronic climate control module, which mine has, or the resistive model, which is only two slide swithches. Gm's technical description to me at the dealer, and on the repair invoice (paid through warranty) was "actuator motor, right hand side" and "actuator motor, left hand side"