Your Heat Pump Freezes Up – Now What?
It’s normal for the outdoor coil in a heat pump system to frost lightly during winter as it circulates frigid refrigerant. Freezing rain may also stick to the coil in cold weather. Occasionally, icing may result from restricted airflow through the coil, usually because of leaves or other debris accumulating in the vent openings. However, when a heat pump coil becomes clogged with solid ice during ordinary operation, it usually indicates a malfunction in other components, particularly the unit’s built-in defrosting system.
All heat pumps incorporate technology to prevent coil icing. Usually, the defrosting is accomplished by reversing the flow of refrigerant so that warm refrigerant circulates from the indoor coil to the outdoor coil and melts the ice. In older units, a timer activates the defroster at regular intervals whether ice is actually forming or not. Technology utilized in newer units includes microprocessor controlled sensors that monitor outdoor temperatures as well as refrigerant temperature in the outdoor coil and activate defrosting only when conditions indicate.
Correctly diagnosing coil icing problems in heat pumps usually requires an HVAC technician with the skills and expertise to perform test procedures. Some of the malfunctions he or she may suspect include:
- A defective defrosting controller module or timer
- Inoperative or improperly calibrated thermostat
- Sticky defroster relay
- Blocked or restricted refrigerant tube in the outdoor coil
- Insufficient refrigerant charge
- Reversing valve solenoid defective
Sobieski Services is your local source for fast, dependable diagnosis and repair of heat pump malfunctions.
Our goal is to help educate our customers in Delaware, Pennsylvania, Maryland and New Jersey about energy and home comfort issues (specific to HVAC & plumbing systems).
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