My air conditioner blows warm air when you first turn it on. If you move the thermostat up and down (from cold to hot) rapidly several times it will start blowing cold air like it is supposed to. At first it would do this every once in a while now it is doing it all the time. Once it come on it stays on, but if you stop engine for a while to run in to a store or something you need to do it again to get it to blow cool.
Air Conditioner only comes on if you move the thermostat up and down on 2007 Chevrolet Trailblazer
you could have several issues with controller or door actuators or doors themselves. seek a diag from a good mech rhat knows these systems. you don't want to get someone that is a hit and miss kinda guy