A frozen heat pump coil is never normal. If your heat pump coils are covered in a layer of ice, this can be a sign of a serious problem in your system. But before you pick up the phone and call us, there are a few things you can do to find the cause. It could be something as simple as water dripping down from a clogged eave.
Minor frost on a heat pump is completely normal. The antifreeze in the system is kept at a temperature below freezing, and as it flows through the coils on the outside of the home, the water vapor in the air condenses on the outside of the coils. The system does have a defrost mode that cycles hot fluid through the coils on a set schedule to remove this frost. Again, frost is a completely normal part of the heat pump function.
Ice, however, is not something that you should see on your heat pump. A frozen heat pump coil can be caused by four possible mechanical issues: Poor airflow, low refrigerant levels, a malfunctioning fan or a failing defrost-system reversing switch.
- Poor airflow around the condenser coils will prevent water vapor from being transferred away from the coils when the defrost system is engaged.
- Low refrigerant levels can prevent the coils from heating sufficiently to melt frost.
- A malfunctioning fan can completely stop the flow of air around a heat pump system.
- A reversing switch allows the refrigerant in the system to run both hot and cold through the coils. If this switch does not function, the refrigerant can be stuck in cold-flow mode.
- If your heat coil is frozen, you can temporarily clear the ice by closing most of the vents in your home and putting the heat pump in cooling mode for 15 to 20 minutes. This will usually force the system to defrost.
Our goal is to help educate our customers in the Mid-Ohio area about energy and home comfort issues (specific to HVAC systems). For more information about heat pumps and other HVAC topics, visit our website.