I know this is a longshot here, but figured I'd give it a try: So I bought a honeywell non programmable thermostat to replace an old honeywell round one. I wired everything up the way I thought it should be, but the AC stays on below the set point. So if I set it to 76 it continues running below that without shutting off. It does turn off by flipping it from Cool to Off. Old thermostat: http://img818.imageshack.us/img818/4601/img0176ix.jpg New thermostat: http://img845.imageshack.us/img845/4568/img0179g.jpg I called Honeywell on it, and the dude basically said there is no problem unless it does this 14 days later. He was saying they have a 14 day learning period. I think it not turning off several degrees below the set point is an actual problem and not some learning period. I can't see how the wiring could be messed up... There is a jumper to switch on the back if you have a heat pump and some other form of AC, but this is on a regular electric and normal AC unit. Although I may switch the jumper anyway..