Heat pump quit heating in late winter - has sat unused since. Technician attended a few days ago and discovered that the unit has no charge and that it had been released through the "safety plug", which blows-out once it reaches a certain temperature. With the system idle (just AH blower running) a pronounced hum was found to be coming from the reversing valve solenoid.
In addition to the humming, the solenoid becomes hot to the touch and vibrates at a high frequency. With it powered, I disconnected and re-connected the solenoid coil lead and heard a pronounced click from the reversing valve. I assume there is at least some motion.
The unit (a Carrier) failed during the heating cycle. Does this tend to indicate a jammed valve or a faulty solenoid?
Thanks so much,