Maybe.. I know the unit has some sort of temperature sensor that causes it to switch from auxilliary to gas heat when it drops below x degrees outside, when I am actually using the heat... but it seems to me that it shouldn't kick on the gas furnace if I have my thermostat set to cool. Could it possibly be that the contractors wired something wrong? Not an hvac expert by any means, just trying to work this out logically. The thermostat correctly determines inside temp and displays it. Basically unit is set to fan auto, cool, and 70 degrees. It seems to me that the thermostat is working as it should. I had no problems all summer long with the unit, cool cycle worked flawlessly, keeping the house right at 70. Its only now when it gets cool at night that this is happening. The unit should simply stay off if it gets below what I have set on the thermostat, but because of some flaw when the outside temp sensor reads its below x degrees the unit thinks it should turn on the gas furnace. Its as if its completely ignoring the thermostat settings.