Diagnostic guide
Heat pump iced over outside? Here is what is happening and what to do.
A heat pump iced over outside is normal during cold weather defrost cycles. It becomes a problem if the ice doesn't clear within 30-45 minutes, or if the unit is fully encased. Causes of persistent icing include defrost sensor failure, low refrigerant, restricted airflow, or buried/blocked outdoor unit. Clear snow and debris first. Then call.
Likely causes, ranked by probability
- 1
Blocked outdoor airflow
Snow, leaves, or shrubs preventing defrost.
Likelihood 30%
- 2
Failed defrost sensor
Sensor doesn't trigger defrost cycle.
Likelihood 30%
- 3
Low refrigerant
Reduces capacity and increases ice buildup.
Likelihood 25%
- 4
Defrost board failure
Board doesn't initiate defrost cycle.
Likelihood 15%
What you can try first
- · Clear snow and debris from around the outdoor unit
- · Turn the system off and let ice melt naturally
When to call us: Ice returns within 4 hours of 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 iced over outside dangerous?
Most causes of "heat pump iced over outside" are not immediately dangerous, but ignoring them can damage the system or raise repair cost. Ice returns within 4 hours of 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.