In the humid Seattle winter, outdoor coils on heat pumps naturally ice over. The Defrost Cycle is designed to temporarily switch the unit into cooling mode to melt that ice. If your unit is encased in a block of ice, the defrost sensor or the control board logic has failed. We test the resistance of the sensor to ensure it accurately detects coil temperature.
Why is there ice on my outdoor heat pump?
A thin layer of frost is normal, but heavy ice buildup indicates the system isn’t entering its defrost cycle. This is usually caused by a faulty sensor, a failed defrost timer, or a malfunctioning reversing valve solenoid.
Reliable Winter Comfort
Get your heat pump calibrated for the Pacific Northwest climate.
- Learn: Modern Comfort Solutions
- Support: About A/C Dr. Naz