I have a Rheem heat pump unit that burned the 24VDC transformer out. I replaced it and burned the replacement up. I replaced it again and took a 3 amp breaker and placed it between the thermostat wires and the outside unit. I found that 1 of the wires that goes directly from the thermostat to the outside unit trips this breaker when I start the unit up. I tested by running new wiring and found that the wiring is okay. But I do not know what is causing the problem. Is it the thermostat or the board in the outside unit? Any help would be greatly appreciated. I have a 6 wire heat pump thermostat. Wire is Y that is giving me trouble.