Running in summer, a heat pump behaves exactly like an air conditioner, so most of the faults are the same. The exception is the reversing valve.
Know where to stop
Everything below is a check any homeowner can safely make. Anything involving opening a sealed refrigerant circuit, working inside an energized panel, or dismantling a gas train needs a licensed technician — not because we want the call, but because that is where people get hurt.
If you smell gas, leave the building and call the gas utility from outside.
Free things to try before you call
A good share of the calls we go out on turn out to be one of these. Try them first, and you may save yourself a service charge.
- 01
Check the thermostat is on COOL with the fan on AUTO and the setpoint below room temperature
- 02
Replace the air filter
- 03
Check breakers for both indoor and outdoor units, and the outdoor disconnect
- 04
Clear vegetation and debris back from the outdoor unit
- 05
Check for ice on the refrigerant lines — switch cooling OFF and fan ON if you find any
- 06
Open all supply registers and unblock return grilles
- 07
Check the condensate drain has not backed up and tripped the float switch
What it probably is
These are the most likely causes. Open one to see what it looks like and what fixing it involves.
1A stuck reversing valve
This is the fault unique to heat pumps. If the valve fails to shift into cooling, the unit runs in heating mode — blowing warm air in July. It is unmistakable once you know to look for it.
2Low refrigerant from a leak
The signs are weak cooling that gets worse over weeks, long run times and ice on the lines. The leak needs finding and repairing, not just a recharge.
3A failed capacitor
The compressor or fan motor hums but does not start. It is a common, inexpensive part, and it usually fails on the hottest day of the year.
4Dirty coils
A fouled outdoor coil cannot reject heat, so the system runs endlessly and cools poorly. Annual maintenance prevents it.
5A failing compressor
The signs are high amp draw, breaker trips, or no start with a known-good capacitor. On an older heat pump, this is usually when replacement is worth discussing.
Common follow-ups
My heat pump blows warm air in summer.
Most likely the reversing valve stuck in heating mode. It needs a technician — but it is a well-understood fault with a clear diagnosis.
Does a heat pump cool as well as a regular AC?
Yes. In cooling mode it is the same refrigeration cycle with the same components. Efficiency ratings are directly comparable.
Why does my heat pump run more than my neighbor’s AC?
It may not be — but heat pumps often run longer, gentler cycles by design, which is better for humidity control. Constant running that never satisfies the thermostat is a different matter and worth a call.
Prefer to call?
(423) 357-1922- Office hours
- Monday to Friday, 8–5
- Outside those hours
- Emergency service is available — call the same number.
- Where we go
- Church Hill, Kingsport, Mount Carmel, Surgoinsville, Rogersville, Johnson City, Bristol, Greeneville, Morristown and across into Southwest Virginia. Full service area.
- Where we are
- 119 E Main St, Church Hill, TN 37642
Still not working after these checks?
That is what we are here for, and emergency service is available.
(423) 357-1922