Diagnostic guide
Heat pump blowing warm air in cooling mode? Here is what is happening and what to do.
A heat pump blowing warm air in cooling mode is almost always a refrigerant problem or a stuck reversing valve. Less commonly, the system is set to 'fan only' or the outdoor unit isn't running. If the outdoor unit isn't spinning, check power. Otherwise this needs a tech.
Likely causes, ranked by probability
- 1
Stuck reversing valve
Valve stuck in heat mode position.
Likelihood 35%
- 2
Low or no refrigerant
System can't move heat without refrigerant.
Likelihood 30%
- 3
Mode set incorrectly
Set to fan or heat instead of cool.
Likelihood 20%
- 4
Outdoor unit not running
Power or component failure at outdoor unit.
Likelihood 15%
What you can try first
- · Confirm mode is set to cool, not fan or heat
- · Verify outdoor unit is running
When to call us: Mode is correct, outdoor unit runs, and the air is still warm.
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 blowing warm air in cooling mode dangerous?
Most causes of "heat pump blowing warm air in cooling mode" are not immediately dangerous, but ignoring them can damage the system or raise repair cost. Mode is correct, outdoor unit runs, and the air is still warm.
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.