Troubleshooting guide
Heat pump frozen coil? Here is what is happening and what to do.
A briefly frozen outdoor coil during cold weather is normal, the system periodically defrosts itself. Persistent ice that doesn't clear within 30 minutes points to a refrigerant problem, a defrost sensor failure, or a defrost board issue. Turn the unit off and call a pro to avoid compressor damage.
Likely causes, ranked by probability
- 1
Failed defrost sensor
The sensor that triggers the defrost cycle has failed.
Likelihood 35%
- 2
Low refrigerant
Reduced capacity means more frequent and longer freeze periods.
Likelihood 25%
- 3
Defrost board failure
The control board that initiates defrost is faulty.
Likelihood 20%
- 4
Blocked outdoor airflow
Snow, leaves, or shrubs restricting airflow.
Likelihood 20%
What you can try first
- · Clear snow and debris around the outdoor unit
- · Ensure 18+ inches of clearance on all sides
When to call us: Ice persists for more than 45 minutes after clearing the area.
When a cleaning helps, and when to call a repair pro
A good portion of “something is off” symptoms (musty smell, weak airflow, water dripping from the indoor unit, surface mold) trace back to a dirty blower wheel, clogged drain, or biofilm on the coil. A full disassembly cleaning solves those. If we get on site and find an electrical or mechanical fault (a failing capacitor, a stuck reversing valve, refrigerant issues), we will tell you and recommend a heat pump repair contractor. We do not do repairs ourselves.
Frequently asked questions
Is heat pump frozen coil dangerous?
Most causes of "heat pump frozen coil" are not immediately dangerous, but ignoring them can damage the system over time. Ice persists for more than 45 minutes after clearing the area.
Can a cleaning fix this?
Sometimes. Biofilm, dirty coils, and clogged drain lines often resolve after a deep clean. Mechanical or electrical issues need a heat pump repair contractor instead.
Do you do repairs?
No. We focus on cleaning and twice-yearly maintenance. If your system needs a part replaced or an electrical fix, we will tell you what we see and recommend a repair contractor.
Try a cleaning first.
If the symptom traces back to a dirty unit, we can fix it. If it does not, we will tell you and point you to a repair pro.