It is a matched system. No furnace. I live in Florida. Lately we've had cold, by our standards, weather in the low 40's at night. Just checked it. It shows "Heat Pump" "System on" with only the AH running. The outside condenser is not running. Thermostst perhaps??
Probably a problem with the unit. Has your electric bill been higher this winter then normal.
Agree with bald looney some sort of pressure switch.. Air flow restriction or possible inadequate refrigerant charge.. Too much too little. Possible refrigerant leak... You can never rule out electronics but I highly doubt it.. Call a professional