A heat pump has a 4 port, solenoid valve that reverses the coils for heating. This valve can sometimes stick. Get up on top and when the unit has been shut down, set it for heat pump and start the unit and let it run. Tap on the solenoid body with a plastic or rubber mallet. Once you have verified that the unit is heating, shut it down fro 5 minutes. Swich the controls back to cooling and have someone start it and you rap on the solenoid body. The unit should switch to cooling.
If it does not switch, check the solenoid coil to be sure it is working. Be very careful when you are up top with the cover off and the unit is operating. Stay away from the fan and any electrical.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot