I have a 2001 Gran Prix. It has the duel zone climate controls. The problem is that I get heat from one side and cold air out of the other. The Heat only comes on if you hold the sliders in just right. So I am pretty sure this means it is the controls not the core or the doors inside the dash.
My question is can I change the controls over to the single zone heat. I might be able to get one from a scrap yard and not have to worry about the sliders. I saw in the Pontiac Aztec thread that the cars with the single control unit will interchange with the double since it is all the same behind the dash, is this true. I just want working heat and do not want to pay $450.00 from the dealer for a head unit.

Those individual climate control systems are more than just a control panel, they have all sorts of blend doors and crap inside the dash.

well my 1997 had the same problem (it had the single zone panel) when i replaced it with a wrecking yard panel everything was fine, and now i have dual zone (all models have the dual zone plenum)