Heat Pump Repair Cost: Common Problems and Fixes
Drew Driskle of Drew’s Crew Heating & Air walks through a second-opinion diagnostic call. Another company had already recommended replacing this heat pump without clearly explaining what was wrong.
For how heat pumps compare with furnaces, boilers, and central air, see our complete guide to home HVAC systems.
Related guides:
Getting a Second Opinion Before Replacing a Heat Pump
The homeowner’s situation is a common one. A previous contractor came out for a no-heat call and:
A diagnosis that names the failed part, not just a recommendation to replace, is what separates a legitimate repair conversation from a sales pitch. This call shows what that diagnostic process looks like.
How a Heat Pump’s Heating and Cooling Modes Work
Cooling Mode
In cooling mode, a heat pump works just like a standard air conditioner:
A low-voltage signal energizes the outdoor contactor.
The contactor lets full voltage reach the capacitor, which supports the compressor and condenser fan motor.
Refrigerant cycles through the system, making the indoor coil cold and the outdoor coil hot.
Heating Mode
A heat pump has one added component: the reversing valve. It flips the direction of refrigerant flow for heating mode.
The indoor coil becomes the hot coil.
The outdoor coil becomes the cold coil.
The system pulls whatever heat is available from the outdoor air and moves it inside.
The Defrost Cycle: Why Heat Pumps Need It
Why the Outdoor Coil Frosts Over
In heating mode, the outdoor coil is the cold coil, which makes it vulnerable to frost in cold weather. Anytime that coil drops below 32°F, frost starts to form. Left alone, that frost becomes a solid block of ice.
How the System Knows When to Defrost
Two sensors work together:
The difference between the two readings is called the delta-T. It tells the defrost board when it’s time to step in.
What Happens During Defrost
The defrost cycle lasts roughly 45 to 90 seconds. During that time:
The reversing valve temporarily switches the system back to air-conditioning mode, so the outdoor coil becomes the hot coil again.
The outdoor fan stops. Blowing cold air across a coil you’re trying to warm would work against the process.
Electric heat strips turn on inside to offset the cold air still coming out of the vents.
Once the outdoor coil is warm enough, the reversing valve switches back to heating mode and normal operation resumes.
The sensors, defrost board, reversing valve, and heat strips all have to work together correctly. That’s exactly where this diagnostic call ran into trouble.
Diagnosing a “No Heat” Call: Starting With the Basics
What the Technician Found on Arrival
The outdoor breaker was already switched off.
The indoor fan was running.
The outdoor contactor wasn’t pulling in.
The First Diagnostic Step
The first step was confirming the thermostat was sending a call for heat to the outdoor unit. That meant checking for voltage between the R and Y terminals at the low-voltage wiring.
While tracing the wiring, the technician found a yellow wire that had come loose and wasn’t connected at all. Reconnecting it got the contactor to pull in, which solved part of the original complaint.
The Lesson
This is a common lesson in HVAC diagnosis. Checking basic wiring connections before assuming a major component has failed saves time and money.
When the Problem Is the Defrost Board, Not the Reversing Valve
A Second Problem Appears
With the contactor now working, a separate issue surfaced:
The reversing valve made an audible whooshing sound.
The contactor began switching off and on by itself.
This seemed to be triggered just by handling the reversing valve’s wiring.
Isolating the Cause
Instead of assuming the reversing valve had failed, the technician isolated the variable. He disconnected the reversing valve from the defrost board entirely and ran the system without it.
With the reversing valve unplugged from the board, the erratic clicking stopped completely. That pointed to the defrost board itself, which was malfunctioning and cycling the reversing valve improperly. The reversing valve and its wiring were not the problem.
Why This Matters for Repair Cost
A reversing valve replacement and a defrost board replacement are two different repairs at two different price points. Correctly isolating the failed component keeps you from paying to replace a part that was never the problem.
Why Age and Refrigerant Type Matter in the Repair Decision
Two factors affected whether repair or full replacement made more sense for this system:
Rather than pushing one answer, the homeowner was given both options:
This respects the homeowner’s own priorities. Some want to minimize near-term cost. Others want to minimize future breakdowns on an aging, harder-to-service system.
What Heat Pump Repair Typically Costs
Repair costs depend on which component failed. Correctly diagnosing that component, rather than guessing, keeps the repair cost in line with the problem. For the most expensive item on this list, see our guide to compressor replacement cost.
Common Repair | Typical Cost |
|---|
Capacitor replacement | $150 – $400 |
Contactor replacement | $150 – $400 |
Defrost board replacement | $300 – $600 |
Reversing valve replacement | $450 – $1,200 |
Crankcase heater replacement | $150 – $350 |
Refrigerant leak repair | $300 – $1,500 |
Compressor replacement | $1,500 – $3,000+ |
Why Reversing Valve Replacement Costs More
Replacing a reversing valve is much more involved than swapping an electrical part like a defrost board or capacitor. It requires:
Recovering the refrigerant
Cutting into the sealed system to swap the valve
Recharging the system afterward
What to Look for When Hiring a Heat Pump Repair Technician
Use this checklist when talking to technicians:
Ask for the specific failed component, not just a recommendation to repair or replace. A technician who can explain what’s wrong, the way this call isolated the defrost board, gives you solid information to decide with.
Get a second opinion if a previous company recommended full replacement without a clear explanation. It’s a reasonable, common step, not an insult to the first technician. This call is an example of a second opinion finding a specific, repairable issue.
Ask how they tell a failed reversing valve from a failed defrost board. Both can cause similar symptoms but need very different repairs at different price points.
Factor in R-22 if your system is old enough to use it. Refrigerant cost and availability change the math of repairing versus replacing an aging system.
Final Thoughts
A heat pump recommended for full replacement isn’t always beyond repair. In this call, methodical troubleshooting found a specific, fixable defrost board issue, where the previous company had only offered replacement without explanation.
Before committing to a full system replacement, it’s worth getting:
If you’re in the Newtown, Pennsylvania area, Drew Driskle and the team at Drew’s Crew Heating & Air can be reached at (215) 964-6683.
Elsewhere, Home Services Pros puts you in touch with licensed heat pump technicians in your area for free, no-obligation estimates, or you can call (833) 586-2038.
Frequently Asked Questions
What does a thorough heat pump repair diagnosis involve?
A thorough diagnosis starts with the basics before assuming a major component has failed: checking disconnects, wiring connections, and whether the thermostat is sending a call for heat or cooling. In this case, a loose wire was part of the original problem. A separate defrost board issue was found by testing the reversing valve independently of the board.
How much does heat pump repair cost?
Heat pump repair costs vary by component:
Capacitors and contactors: $150 to $400
Defrost board: $300 to $600
Reversing valve: $450 to $1,200, due to the refrigerant recovery and recharging involved
Compressor: often $1,500 to $3,000 or more, the most expensive common repair
How can you tell if it’s the reversing valve or the defrost board that’s failing?
One approach is to disconnect the reversing valve from the defrost board and run the system without it. If the erratic behavior in the contactor or reversing valve stops, the defrost board is the likely cause, not the reversing valve or its wiring.
Should I get a second opinion if a company recommends replacing my heat pump?
Yes, especially if the recommendation doesn’t clearly explain what failed. A proper diagnosis should identify the failed component. A second opinion can sometimes find a repairable issue the first assessment didn’t fully investigate.
What is a heat pump’s defrost cycle, and why does it matter for repairs?
The defrost cycle temporarily reverses the system to melt frost that builds up on the outdoor coil during heating mode. It relies on a defrost board, temperature sensors, and the reversing valve working together. A problem in any of these parts can cause similar-looking symptoms that need different repairs.
Does it matter if my heat pump uses R-22 refrigerant?
Yes. U.S. production of R-22 ended in 2020, and the remaining supply is limited and expensive, which raises the cost of any refrigerant-related repair. Combined with the age of the rest of the system, it is a major factor in deciding whether to repair or replace an older heat pump.
