Your heat pump freezing up on a cold Baltimore winter night or hot summer afternoon is a frustrating situation, but not always a complex one. By checking for the most common causes of freezing, you’ll know if the problem is something you can solve or if you’ll need a professional.
Impaired airflow – Without sufficient airflow, the temperature of the refrigerant in the heat pump’s condenser and evaporator coils falls below freezing. This causes the moisture on these coils to freeze. Check that none of your supply air registers are blocked by furniture, rugs, drapes or other items. Clear away leaves, grass clippings and other debris on or around the outdoor unit. If your air filter looks dirty, replace it with a new one.
Power-saving setting – Running your system on this setting shortens the defrost cycle and is a possible cause of a heat pump freezing up. To prevent this, stick with the manufacturer’s operating specifications.
Cold rain – In cold weather, rain on your outdoor coil can cause ice buildup. To defrost your system, try running the fan (without heat) on the exhaust setting.
Low refrigerant – Too little refrigerant lowers the pressure in your heat pump system, which can cause freezing. Heat pumps don’t “use up” refrigerant, so low refrigerant suggests your system has a leak that will need professional care.
Settled concrete slab – Your outdoor unit sits on a concrete slab designed to keep the unit level. This slab can settle into the ground and tilt so the unit becomes uneven, interfering with the drainage of ice melt. If your outdoor condenser/compressor looks uneven, contact a heating and cooling professional.
Damaged defroster – If your heat pump’s defrost cycle won’t start, try moving the ice sensor on the outdoor unit closer to the air intake area. If this doesn’t help, the sensor or the defroster might be damaged.
If your heat pump freezing up is a regular occurrence or you suspect your system needs professional care, contact us at Griffith Energy Services, Inc. for help. We provide dependable expert services around Baltimore, Frederick, and Manassas, as well as in and around Dover, Del., and Martinsburg, W.Va.
Written by Kevin Spain