A heat pump moves heat rather than making it, and reverses to heat the house in winter. That gives it two faults no air conditioner has: a reversing valve that can stick or fail, and a defrost cycle that has to clear frost off the outdoor coil. It also relies on electric heat strips inside the air handler as auxiliary heat. Cool air from the registers in winter is often normal operation rather than a fault, and telling the difference is the first job on any heat pump call.
How a heat pump works, and why it feels different
A furnace burns fuel and makes heat. A heat pump does not make heat at all — it collects it from the outdoor air and moves it indoors, and in summer runs the same cycle in reverse. One outdoor unit and one indoor air handler do both jobs all year.
That has consequences a homeowner feels straight away. Supply air in heating mode is warm rather than hot, so it can feel cool against your hand even when the system is working perfectly. The outdoor unit runs in winter, ices up in cold damp weather, and periodically reverses itself to melt that ice off — steaming and blowing cool air indoors for a few minutes while it does.
- The outdoor unit is a heat pump condensing unit, not a plain air conditioner condenser. It contains a reversing valve.
- The indoor unit is an air handler, not a furnace, and it carries an electric heat strip kit — commonly 10 kW, and 15 kW on larger systems — as auxiliary and emergency heat.
- The thermostat has to be wired and configured for a heat pump, including the auxiliary and emergency heat stages. A thermostat that is not set up for the equipment will run the strips when it should not; see thermostat installation.
Why a heat pump blows cool air in winter
This is the most common heat pump complaint we take, and often nothing is broken. Working through it in order:
- Normal supply temperature. Heat pump supply air is warm, not hot. If the house is holding temperature, the system is doing its job.
- A defrost cycle. For a few minutes the outdoor unit reverses to melt frost off its coil, and the indoor air goes cool. It ends by itself. If the outdoor unit is buried in ice and never clears, the defrost control, the sensor or the outdoor fan is the fault.
- Failed auxiliary heat. If the electric heat strips are not energizing, the system loses its backup on the coldest days. The strip kit, its contactor or the thermostat staging are the places to look.
- A failed reversing valve. The valve that switches between heating and cooling can stick or fail outright. We have diagnosed and replaced one on an installed heat pump, claimed as a stock part failure under the distributor's parts warranty.
- Low refrigerant. A heat pump short of charge cannot collect heat outdoors. Called to no heat at a building with two heat pump systems, we found both units out of refrigerant, a leak inside an air handler evaporator coil and a clogged filter restricting airflow.
Common heat pump problems and what they mean
- Outdoor unit will not run at all
- Start with the outdoor disconnect and its fuses, then the contactor and the run capacitor. A burned capacitor is one of the most frequent findings on a failed heat pump, and we have found it alongside low refrigerant and a weak compressor on the same unit more than once.
- Runs constantly and never satisfies
- Low charge, a fouled coil, restricted airflow or a compressor no longer pumping properly. All four are measurable rather than guessable.
- Very high electric use in winter
- Usually the auxiliary heat strips running when they should not, which points at the thermostat configuration, a stuck stage, a defrost fault or a compressor that is not contributing.
- Ice on the outdoor unit that never clears
- The defrost cycle is not completing. Defrost board, defrost sensor, outdoor fan motor or a reversing valve that will not shift.
- Water around the indoor air handler
- The condensate path is blocked or the pump has failed. We fit an EZ trap with a safety switch, and attic equipment gets a drain pan with a float switch to shut the system down on overflow.
- Weak or noisy airflow
- Filter, blower assembly, return sizing or duct. We have found an indoor unit with no return air at all, which no equipment work would have fixed.
Auxiliary and emergency heat: what the heat strips do
Inside the air handler is an electric resistance heat kit, there to supplement the heat pump when it cannot keep up on a cold day and to heat the house on its own if the outdoor unit fails. The kits we install are commonly 10 kW, with 15 kW on larger systems and 5 kW on small ones.
- Auxiliary heat comes on automatically alongside the compressor when the house is losing ground. That is designed behavior.
- Emergency heat is a setting you choose, which locks the compressor out and heats entirely on the strips. Use it if the outdoor unit has failed, and call us — it is not meant to run for weeks.
- Strips that run constantly usually mean the compressor is not doing its share, the thermostat is staged wrongly, or the unit is stuck in defrost.
- The electrical supply has to support it. Where a panel cannot carry the load we have run a dedicated 6/3 line around sixty to seventy feet to a basement for an electric furnace or heat pump, in one-inch conduit with junction boxes, and consolidated existing circuits onto tandem breakers because the panel had no spaces left — see electrical panel upgrades and replacement.
What a heat pump repair call includes
- Establish the mode. Whether the system is in heating, cooling or defrost when we arrive changes what the readings mean.
- Check airflow first. Filter, return, blower and coil. A clogged filter has been the restriction behind more than one no-heat call we have taken.
- Read the refrigerant side with gauges, and verify the charge by subcooling rather than by pressure alone.
- Leak search if the charge is low. Refrigerant does not get used up. We have repaired leaks, added a measured charge — 6.5 pounds of R-454B across two systems on one call — and applied a fast-seal leak treatment where that was the right repair.
- Test the reversing valve, the defrost control and the strips. These are the checks that separate a heat pump call from an air conditioning call.
- Clean the coils. We chemically clean evaporator coils and condenser coils, and on some calls that has been the whole repair.
- Check the warranty before recommending replacement. Registration is mandatory for the extended parts coverage manufacturers offer, and we have completed distributor warranty claims with the install date, service date, model and serial number to get a part covered.
Where the outdoor unit is a straight air conditioner condenser rather than a heat pump, the fault list is different and the page you want is air conditioning repair.
Heat pump repair or replacement: how to decide
Most heat pump faults are repairable, and we would rather repair. A specific combination of findings is what moves us to recommend replacement:
- Low refrigerant, a burned capacitor and a weak compressor together. We have written this up more than once, and it is a failed system rather than a failed part.
- A leak inside the evaporator coil on an aged system. The coil and the outdoor unit are a matched pair and both are near the end.
- An R-22 system with a genuine leak. The refrigerant is obsolete; equipment still running it is old by definition. We recover R-22 legally before anything is removed.
- Repeated failures across separate components. When the capacitor, the contactor, the defrost board and the reversing valve have each had their turn, the next part will not be the last.
Where a homeowner is coming off gas heat instead, we have removed gas furnaces and condensers and installed heat pump and air handler systems with supplemental electric heat strips in their place. The sizing side of that is covered on air conditioning installation.
What a heat pump installation includes
A changeout follows the same discipline as any refrigerant work, with the outdoor unit and the indoor air handler replaced as a matched pair:
- Recover the existing refrigerant legally — R-22 on older systems — and remove the outdoor unit, air handler, old heat strips, drain pan, drain line, pad and disconnect.
- Flush the line set with RX11 and nitrogen to drive out old oil and moisture, then pressure-test at 150 psi.
- Set the outdoor unit on a new pad, 32 by 32 being our standard size, with four pump-up risers to lift it clear of the ground, a new disconnect box and a new electrical whip.
- Set the air handler with a new electric heat kit, a new return box or boot, and the supply and return plenums attached. Variable speed air handlers pair well with higher-efficiency outdoor units.
- Rebuild the condensate path with a new drain line and an EZ trap, and on attic equipment a drain pan with a float or flow switch.
- Evacuate to 500 microns, charge by subcooling to the manufacturer's specification, and verify the result by temperature split across the coil.
- Run the system in both modes and confirm the reversing valve, defrost and auxiliary heat all behave before handover.
Where there is no existing system at all, we build one — complete central heat pump systems in houses that had only a boiler and baseboards, with new ductwork, registers, a return box, condensate handling and thermostat wiring from scratch.
Ductless mini split heat pumps
Where duct cannot reasonably be run — an addition, a converted space, a room the existing system was never designed to reach — a ductless system is the answer. It is still a heat pump, distributing through wall-mounted heads instead of ductwork.
- Single zone. One outdoor unit, one indoor head. We have installed one-and-a-half ton systems running thirty feet of line set, communicating wiring and drain line to the outside, with a 30 amp fused disconnect and a whip to the outdoor unit.
- Multi zone. One outdoor unit serving several heads. We have fitted a two ton head in a living room and a one-and-a-half ton head in a bedroom off a single multi-zone unit, running 25 and 40 foot line sets, drain lines and 240 volt communicating wiring to each.
- Replacements. We have replaced a ductless system serving two bedrooms, recovering the R-22 in the old lines and flushing them with RX11 and nitrogen before connecting new equipment.
- Electrical matters. On one job the plan was to reuse an existing jacuzzi circuit for the outdoor unit, with the caveat written into the contract that a separate electrical scope would be needed if it did not suit the equipment.
How long does a heat pump last?
Twelve to fifteen years is typical, and a heat pump works harder for it than an air conditioner does because it runs in both seasons rather than one. That is the argument for servicing it twice a year rather than once. Our annual service agreement covers two tune-ups with a 24-point inspection at each visit: adjust the blower assembly, test refrigerant, tune the burners, inspect the evaporator coil, clean the ignition assembly, clean and inspect filters and calibrate the thermostat.
The other thing that shortens equipment life is a distribution system that was never right. A unit fighting leaking, undersized or disconnected duct never reaches its rated performance and never stops running; see ductwork repair, sealing and venting.
What heat pump repair and installation cost, and how we price it
We do not quote by phone and we do not publish prices. A heat pump job varies by tonnage, by the size of the electric heat kit, by whether the air handler is in an attic or a closet, by the state of the line set, by electrical capacity at the panel and by whether ductwork has to be built.
An estimator comes to the property, inspects what is actually there, and gives you a written price for a defined scope before anything is ordered. Our work is performed according to the Virginia building code, and permit and processing are included in the contract where the job requires them.