Help! My Heat Pump is Frozen outside!
- Haskell Heating And Air
- Feb 21, 2023
- 2 min read
Updated: Aug 16, 2024
The Problem
A customer reports that their heat pump system is not heating properly, and the outdoor heat pump has a lot of ice covering it.
Possible Causes
During heating operation, a heat pump actually drops the refrigerant temperature to below the outdoor temperature to harvest heat from the air. This means the metal coil is likely below 32 degrees and ice will start to form on the coil. At a certain point the unit will enter a defrost mode and melt the ice to prevent a major buildup. A faulty reversing valve, sensor, computer board, or metering device/ refrigerant charge issues can cause this problem.
Diagnosis
While inspecting the outdoor unit, you may find that the defrost board has burn marks. This indicates that you may need to order a new defrost control board under your warranty with the equipment manufacturer.
Solution
To address the issue, run the unit in its cooling cycle for a few minutes to melt most of the ice, and then keep the unit running in auxiliary/emergency heat. This was to ensure the customer had heat while we waited for the board to come in. We then replace the defrost board.
Homeowner Tips
Inspect your heat pump equipment periodically to catch any potential issues. Keep in mind that a light layer of frost is normal, but if the buildup becomes thick, call a technician. Most units defrost every 30-90 minutes. Auxiliary heating in most setups involves running gas or electricity, and at low outdoor temperatures, heat pumps may struggle to keep up, causing them to activate their auxiliary heat through sensors or timers.
Tech Tips
To test a defrost, use a jumper, test pin, and follow the steps on the board or unit panel. Make sure that defrost sensors are attached, and that all steps of the defrost cycle are activated. The fan should stop, the reversing valve should switch over, and the compressor should run. The indoor unit should activate aux. heat and continue to run.
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That is so helpful in these colder months!