Heat pump won’t start

— Check that the filter pump is on — Check the thermostat. It could be set too low.

— Time delay may be on — Check circuit breaker/fuses — Ensure adequate water flow— check valves/bypass

Heat pump won’t heat

— Ensure that the heat pump is the appropriate size — Check time clock.

The heat setting may be too short to complete heating needed. Extend the hours and/or install an automatic override if necessary — Check that the compressor is on. The compressor could be off with the fan running — Ensure that the air temperature leaving the heat pump is cooler than the surrounding area. It should be 6 to 12 °F cooler than ambient air

Heat pump cycles are too short

— Check the water flow. The high— pressure switch may be interrupting operation when there is inadequate water flow — If there is a loss of refrigerant, the low—pressure switch can interrupt operation. *You must be HVAC certified to work on refrigerant components.

— Check the low ambient switch and thermostat.

When the surrounding air is 45 °F, the low ambient switch may interrupt operation.

The wet bulb controller can be calibrated for different temperatures and can operate to 30 °F.