Diagnostic guide
Heat pump not cooling? Here is what is happening and what to do.
A heat pump that won't cool usually has one of three problems: dirty coils restricting heat exchange, a refrigerant leak, or an iced-over indoor coil from a clogged filter. Filter and outdoor coil cleanliness account for the majority of cases we see. Refrigerant leaks require professional diagnosis.
Likely causes, ranked by probability
- 1
Dirty outdoor coil
Restricts heat rejection. Most common cause we see in summer.
Likelihood 35%
- 2
Clogged filter and iced indoor coil
Restricted airflow causes the indoor coil to freeze.
Likelihood 30%
- 3
Low refrigerant
Slow leak reducing capacity.
Likelihood 20%
- 4
Failed capacitor on outdoor unit
Compressor or fan won't start.
Likelihood 15%
What you can try first
- · Wash the indoor filter
- · Rinse the outdoor coil with garden hose at low pressure
- · Turn the system off for an hour if the indoor coil is iced
When to call us: Outdoor coil is clean, filter is clean, and the system still won't cool.
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 not cooling dangerous?
Most causes of "heat pump not cooling" are not immediately dangerous, but ignoring them can damage the system or raise repair cost. Outdoor coil is clean, filter is clean, and the system still won't cool.
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.