Frozen Heat Pump Coils? Learn What To Do

If your heating bills have crept up to startling proportions since last season, it could indicate a heat pump maintenance issue, such as frozen heat pump coils. Take a look at the heat pump’s outside cabinet. If it has more than a light frost on the coils, you have an issue that requires attention.

Air-source heat pumps deliver up to 400 percent heat energy for the energy consumed when they are well maintained. Correct refrigerant charge, free airflow and all components pulling their share of the load are required for peak performance, defined by efficient heat extraction and heat release at the coils.

Frozen heat pump coils

In heating mode, the outside coil becomes extremely cold. Free airflow is key to preventing ice accumulation. Blockages that prevent or hinder airflow across the coil permit moisture in the ambient air to condense on the cold coil, and freeze and accumulate into a block of ice. Check the outdoor cabinet often for debris, ice and snow accumulation and any other blockages that can lead to frozen heat pump coils.

More technical heat-pump performance issues that cause frozen coils are a matter for your HVAC professional:

  • If defrost mode is not functioning properly, there could be an issue with the reversing valve sticking or malfunctioning, or a bad defrost timer, sensor or relay.
  • If the outdoor blower has failed, there’s no airflow across the coil at all, which is required to prevent freezing.
  • Incorrect refrigerant charge can cause ice accumulation on the coil. Refrigerant must be measured and charged by a certified professional. Incorrect refrigerant charge could also indicate a leak in the system.
  • Bad electrical contacts and components overburden the heat pump, which often causes ice accumulation.

Tip: If you notice the thermostat calling for “Emergency Heat” (backup electric-resistance heat) much too often, check your outdoor cabinet for ice accumulation. Backup heat should only be active during defrost mode, sub-freezing temperatures and when the indoor temperature is two or more degrees below the thermostat setting.

If you have frozen heat pump coils or other HVAC issues, please contact us at Jackson & Sons today. We’ve provided unmatched service for homeowners in eastern North Carolina since 1974.

Our goal is to help educate our customers in Eastern North Carolina (including Wayne, Johnston, Greene, Lenoir, and Duplin Counties) about energy and home comfort issues (specific to HVAC systems).  For more information about frozen heat pump coils and other HVAC topics, download our free Home Comfort Resource guide.

Image courtesy of Shutterstock

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