Diagnostic 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.
Our diagnostic process
We arrive within a one-hour window, inspect the system end-to-end, read any active error codes, test temperatures and pressures, and identify the actual cause. You get a written quote before any repair work starts. The $129 diagnostic fee is applied to any repair you proceed with.
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 or raise repair cost. 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 require a diagnostic visit instead.
How much does diagnosis cost?
Our diagnostic visit is $129 flat, applied to any repair you proceed with. We will quote any repair before starting work.
Need a tech to take a look?
$129 flat diagnostic. Same-week scheduling across Vermont. Credited toward any repair.