My compressor/fan unit runs constantly, even with the thermostat turned off. The only way to disable it is to trip the breaker leading to the unit. I have examined the wiring and can find nothing apparently wrong. I was confused to find a two lead wire running from the furnace to near the compressor. It simply ends without connecting to anything. Since the ends are sealed, I can only assume this is how it is supposed to be. Any thoughts/suggestions?