I have a Trane XE 800 heat pump. The AC cycle works fine but now we have switched over to heat and the AC will not disconnect outside. I have since flipped the breaker on the outside unit and we are runnning the AUX heat until we can figure out why. Please help. Thanks.

Was the compressor running? Or just the fan motor?

Maybe the contactor is stuck?

was the compressor running? or just the fan motor?

Compressor and fan run but stay in AC mode. Switch over valve may not be working. I replaced the circuit board and the solenoid gets 25vac. It worked fine in heat and cooling recently. Could it be the valve is stuck or is there an easier fix? Would the thermostat have anything to do with this? Thanks again