A heat pump that heats perfectly all winter and then blows room-temperature air in July is one of the most common calls we get once the first real Puget Sound heat stretch hits. It feels like the whole system died. It usually hasn't.
Here's the useful part: if heating works, most of your system works. The compressor pumps. The fans spin. The refrigerant charge is probably in the ballpark. Everything that makes heating possible also makes cooling possible — because it is the same equipment running in the opposite direction. So when only one direction fails, the problem lives in the part that flips the direction.
The one-sentence diagnosis
Heating works, cooling doesn't, means the changeover isn't happening. That's the reversing valve, the solenoid coil that drives it, the low-voltage wire that energizes the coil, or the thermostat that's supposed to send the signal. Four suspects, and only one of them is expensive.
What the reversing valve actually does
A heat pump doesn't have a heating side and a cooling side. It has one refrigerant loop, and a four-way valve that decides which coil is the hot one.
- Cooling mode: the indoor coil absorbs heat from your house, the outdoor coil dumps it outside.
- Heating mode: the valve slides, refrigerant flow reverses, and the outdoor coil absorbs heat from the air outside while the indoor coil releases it into the house.
That sliding is done by a small brass valve with an electric solenoid bolted to it. The solenoid is a coil of wire. When your thermostat energizes the O terminal, the coil creates a magnetic field, a pilot valve shifts, and refrigerant pressure slides the main valve over. If any link in that chain breaks, the system stays parked in whatever mode it was last in — which, in Western Washington, is heating.
Why it fails here
Three things kill reversing valves in the Puget Sound region:
- Age and cycles. The valve moves thousands of times over a system's life, including every single defrost cycle in winter. Wear is normal.
- The solenoid coil, not the valve. Coils burn out far more often than valve bodies stick. Good news — that's the cheap end of the repair.
- Salt air and moisture. In coastal areas like Des Moines, Gig Harbor, Steilacoom and Dash Point, corrosion attacks the coil terminals and the electrical connections long before it touches the valve internals.
Free checks before you call anyone
Do these first. We'd rather you save the diagnostic fee than pay us to flip a switch.
1. Thermostat mode and setpoint
Sounds obvious. It's the single most common cause of "my heat pump won't cool." Confirm the thermostat is on COOL, not HEAT, not AUTO with a setpoint above room temperature. If your thermostat is AUTO with a wide deadband, it may simply never call for cooling until the house hits 78 degrees.
2. The thermostat's heat pump configuration
If someone recently replaced the thermostat — a smart thermostat, a DIY swap, a home sale — this is your prime suspect. Heat pumps use an O or B terminal to energize the reversing valve, and the installer has to tell the thermostat which one your equipment uses. Configure it wrong and the system happily heats and stubbornly refuses to cool. A five-minute settings change fixes it.
3. Breaker and outdoor unit
Walk outside while the thermostat is calling for cooling. Is the outdoor fan spinning? Is the unit humming at all? Heat pumps often have two breakers — one for the indoor air handler or furnace, one for the outdoor condenser. If the outdoor breaker tripped, the indoor blower still runs and you get airflow with no cooling. Reset it once. If it trips again, stop and call.
4. Filter and outdoor coil
A plugged filter or a coil packed with cottonwood, grass clippings and blackberry vine chokes capacity. That usually shows up as weak cooling rather than no cooling, but it's free to check and it's the number one cause of preventable service calls.
If all four pass and the air still isn't cold, it's a real repair. That's what heat pump repair is for.
What the repair costs
Heat pump repairs in our service area run $150 to $1,500 in standard markets, $175 to $1,800 in affluent markets like Seattle and Maple Valley, and $200 to $2,000 in luxury markets like Bellevue and Gig Harbor. Where a no-cooling repair lands inside that range depends entirely on which of the four suspects it turns out to be.
| What failed | Where it lands in the range | Typical time |
|---|---|---|
| What failedThermostat set or configured wrong | Where it lands in the rangeDiagnostic only | Typical timeUnder an hour |
| What failedCorroded or broken O-wire connection | Where it lands in the rangeLow end | Typical timeSame visit |
| What failedReversing valve solenoid coil | Where it lands in the rangeLow to middle | Typical timeSame visit, usually |
| What failedReversing valve body replacement | Where it lands in the rangeTop of the range | Typical timeHalf a day, refrigerant recovery required |
| What failedContactor or capacitor fault | Where it lands in the rangeLow end | Typical timeSame visit |
The reason the valve body itself is the expensive one is simple: it's brazed into a sealed refrigerant circuit. Replacing it means recovering the refrigerant, cutting the old valve out, brazing a new one in without cooking the internal seals, pulling a deep vacuum, and recharging to spec. That's certified work with real equipment, not a bolt-on part.
When it's not the reversing valve at all
A few other failures look identical from the living room:
- Failed contactor or run capacitor. The outdoor unit doesn't start, so nothing gets rejected outside. Cheap fix, low end of the range.
- Low refrigerant from a leak. This usually degrades heating too, just less obviously, because heating in a mild climate hides a lot of sins. If cooling is weak rather than absent, suspect charge.
- Blower running without the compressor. You feel air, so you assume the system is on. Go outside and confirm the outdoor unit is actually running.
- Auxiliary heat locked on. If your thermostat is stuck in emergency heat, cooling is disabled by design.
A good technician checks all of these before condemning a valve, because condemning a valve is the most expensive answer available. Ask what test proved it — a temperature split across the valve body and a check for solenoid voltage are the honest ones.
Repair it or replace it?
The rule we use, plainly:
- Under 10 years old: repair, as long as the fix costs less than half a new system. These units have plenty of life left.
- 10 to 12 years old: depends on the repair. A solenoid coil at the low end of the range is an easy yes. A full valve replacement on a 12-year-old single-stage unit deserves a conversation.
- Past 12 to 15 years, or running R-22: replacement usually wins. R-22 is phased out and expensive, and a big repair on obsolete refrigerant is money you can't get back.
Heat pump replacement runs $10,000 to $16,000 in standard markets, and a full new ducted heat pump install runs $12,000 to $18,000 standard, $13,800 to $24,300 in affluent and luxury markets. Every Varsity install carries a 10-year parts and labor warranty, and most are finished in one day. If you want a ballpark before anyone visits, the instant estimate tool gives you Good, Better and Best starting prices in about 60 seconds. For the full breakdown, our Washington heat pump cost guide walks through what actually moves the number.
On rebates: PSE offers up to $4,400 toward a qualifying heat pump when it replaces an existing electric or fossil-fuel system, and the exact amount depends on what you're replacing and what you install. Programs change — we confirm your current eligibility and handle the paperwork. Since April 2, 2026, PSE rebates require a PSE-certified installer. Varsity is one. And rebates follow the meter, not the county: Tacoma, Fircrest, University Place and Fife are on Tacoma Power, Seattle is City Light, and Gig Harbor and Fox Island are Peninsula Light, each with their own programs.
What a real diagnostic visit looks like
A technician confirms the thermostat call, verifies 24 volts at the reversing valve solenoid, measures line temperatures across the valve to see whether refrigerant actually reversed, checks the contactor and capacitor, and reads system pressures. Then you get a diagnosis and a price before any work starts. If parts are needed, they're ordered and a return visit is scheduled.
If the opposite is happening — cold air in January instead of warm air in July — start with our guide to a heat pump that won't heat, because the free checks are different.
Get it looked at
Service hours are Monday through Friday, 8 to 6, with same-week scheduling across King, Pierce and Thurston counties. Call (253) 785-4622 or request service online. We'll tell you which of the four suspects it is, what it costs, and whether it's worth fixing — including when the honest answer is that it isn't.