To troubleshoot a Miller heat pump, begin by testing the thermostat to see if the setting is accurate or whether the thermostat needs to be reset or reconfigured. The circuit breakers for the heat pump should also be checked to make sure they have not tripped or shut off.
If circuit breakers for a Miller heat pump have tripped, the unit may have a damaged wiring connection, malfunctioning control board or damaged blower motor. When the breakers are operational, the problem could involve the fan relay, low voltage wiring or a malfunctioning thermostat.
If the fan is running on the heat pump, homeowners can troubleshoot the unit by setting the thermostat to emergency heat with a set point of five degrees above room temperature. If warm air is dispersing from the vents, the heat pump problem may involve a malfunction in the outdoor unit.
Homeowners can troubleshoot the outdoor unit of the heat pump by inspecting the appliance for ice or frost build up. A malfunction in the defrost control could be the problem or the unit could be low on refrigerant. If the outdoor fan is running, homeowners can check the high pressure cutout for a fan motor or run capacitor problem or inspect the wiring for malfunctions or damage.