Frozen Heat Pump? Reasons Why It Happens and How to Prevent It

by Greg Leisgang on February 28, 2014

Posted in: Heat Pumps

It can be a baffling and unpleasant predicament to see the heat pump of your West Chester home encased in ice. Before you start chipping away at the ice, learn the common reasons why it happens and what to do, or take steps to prevent it from happening in the first place.

Understanding Your Heat Pump

frozen heat pumpHeat pumps extract, move and release heat energy from one air source to another. Therefore, a stable supply of unrestricted airflow is required for the system to operate properly. Without adequate airflow, the outside heat-exchange coil, when in heating cycle, will accumulate ice, even if the outside temperature is not below the freezing mark. (Proof of this can be seen when the inside coil ices up for lack of airflow during the cooling months in cooling cycle.)

If your heat pump has iced up, follow these steps first:

  • Shut the power off at the circuit box.
  • Melt the ice using a garden hose. Do not use tools to chip away the ice.
  • You can set the heat pump in cooling mode, which sends hot refrigerant through the outside coil and helps melt the ice more quickly. (Note, that if this works, you have eliminated a faulty reversing valve as one of the possible mechanical defects causing ice accumulation.)
  • Once the ice is melted, make sure there are no other obstructions to airflow, such as debris and leaves.
  • Check the air filter. A clogged air filter restricts airflow.

Once the system is back online and heating properly, check the coil every few hours over the course of the next couple of days. If the coil ices up again, you have a mechanical or electrical problem that requires the expertise of your HVAC professional.

Icing issues may often be narrowed down to a bad defrost timer in older systems, or a bad defrost thermostat for newer systems with Demand Defrost function. The thermostat relay may also be faulty.

For more expert advice or assistance with your heat pump, please contact us at Tri-County Heating & Cooling. We've proudly served residents in West Chester and greater Cincinnati since 1969.

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