My car, when I bought it, had the original AC dashpad in it. The car was already 3/4 cloned to a 440SixPack RT, and those did not come with AC. So I switched out the pad, no problem. However, non-AC cars have the underdash knobs for the vents, and the temp / vent controls for an AC car are vacuum operated. With mine, I just left the 3-switch temp control ( which I put in to be more correct for the clone) midway between hot and cold, and since I don't have a vacuum switch to shut off the heat or defrost, I have it blended between the two. That's the main thing here - at least as far as I know, converting an AC car to non-AC, there is really no way to shut the heat off short of disconnecting the heater core. If I'm wrong here, please tell me - I'd love to get my 3-switch control to shut off or start up my heat and /or defrost! The floor gets awful hot in the summer when I'm driving, even with the top down!