Yesterday was the first day that it was warm enough to turn on the air-conditioning. When I switched the thermostat over from heat to cool, the gas furnace (backup heat) came on, rather than the air conditioning. I tried several times, at different thermostat settings, and no matter what I did, the furnace fired up. I switched off the furnace at the breaker, and now the thermostat might as well not be there, because it doesn't do anything. I can't even get the blower to come on without the furncace. I am hoping that this is a thermostat problem, because I really don't know what else would cause this problem. Does anybody out there have any insight?