Goodman heat pump, it hums but will not start, voltage present.

Goodman heat pump, it hums but will not start, voltage present.
Often a compressor does that if it is reconnected to soon after compressing (for instance after a short power cut). Once running the compressor builds up a high pressure in a gas without a sweat, but it (often) fails the power to start compressing in an already high pressure state. So keep the compressor off for half an hour after running. After that period it should restart without any problems. If not the compressor is faulty.
I hope this helped you.
;)

Or it could be a run capacitor/start relay/start capacitor/burnt wire terminal/etc. Check the compressor terminals for grounding and correct impedance.

If all checks out and its not starting(and you do not have a start assist for the compressor) you can add a super boost kit to help the compressor start.