Our furnace turns off (mainly at night when the temperature drops) and the thermostat will still read that the heat is on with a temperature below the set temp. It will then begin to blow cool air to I guess "cool itself off." We've changed the sensor on the furnace several times but this will only last for a couple days before it happens again. Also, if we turn everything off and reboot the furnace, it will work for a couple days until I guess it "over works itself" and does it again. This is beginning to be a pain- especially with a new baby on the way it's very cold at night!!! PLEASE HELP!!!