A heat pump that has stopped working is almost always telling you one of three things: it lost airflow, it lost refrigerant, or it lost a control signal from the thermostat or defrost board. In Fairfax, Virginia, the most common call we run in late October is a system that heats fine in mild weather but blows cold air the first time the temperature drops below 40°F. The rest of this post walks through the specific signs that separate a five-minute fix from a repair you should schedule today.
If you are searching for heat pump repair Fairfax VA, the short answer is this: any symptom that repeats for more than one cycle, or that leaves you without heat or cooling for more than a few hours, is a repair call, not a wait-and-see.
Why Is My Heat Pump Not Working in Fairfax VA?
Heat pump not working Fairfax VA is a category of problem, not a single fault, and the cause usually falls into one of four buckets: airflow restriction, refrigerant loss, electrical or control failure, or a reversing valve that has stuck. Each one produces a different set of symptoms, which is why two neighbors on the same street can both say "my heat pump is broken" and need completely different repairs.
Fairfax sits in a climate zone where heat pumps run in both heating and cooling mode for most of the year. That dual duty is harder on the equipment than a system that only cools. A unit here cycles through defrost roughly every 30 to 90 minutes on a cold, damp day, and each defrost cycle briefly puts the system into cooling mode. If the defrost board or the outdoor sensor fails, the unit can get stuck in that mode and blow cold air into your house for hours.
Our team works on these systems every week across Fairfax and the surrounding areas, and we handle everything from HVAC repair Fairfax VA on single-family homes to full system replacements in older neighborhoods where the original equipment is now 15 to 20 years old.
Signs You Need Heat Pump Repair in Fairfax VA
Signs you need heat pump repair in Fairfax VA show up in three places: what you hear, what you feel, and what the system does over a full cycle. Watch for these.
- Short cycling. The unit runs for 2 to 5 minutes, shuts off, and restarts within 10 minutes. Normal run times in heating mode are 10 to 20 minutes.
- Ice on the outdoor coil. A light frost during defrost is normal. A solid block of ice that stays after the cycle ends is not.
- Air that is only slightly warm. Supply air should run 25°F to 35°F above the return air temperature. If it is 5°F to 10°F above, you have a refrigerant or compressor problem.
- Rattling, grinding, or a hard metallic clunk at startup. That is usually a failing contactor, capacitor, or fan motor bearing.
- Rising electric bills with no change in how you run the system. A heat pump that has lost refrigerant runs longer to hit the same setpoint.
One or two of these on a single cold morning can be a fluke. The same symptom three days running is a repair.
Heat Pump Not Heating in Fairfax, Virginia
Heat pump not heating in Fairfax, Virginia usually means the system is running but not delivering warm air, or it is running in cooling mode when it should be heating. Start by checking three things yourself before you call anyone.
- Set the thermostat 3°F to 5°F above room temperature and give it 10 minutes. Heat pumps ramp up slowly and do not respond like a gas furnace.
- Confirm the thermostat is set to HEAT, not AUTO or COOL, and that the fan is on AUTO.
- Check the outdoor unit. If it is buried in leaves or covered in ice, clear the leaves and let the defrost cycle run.
If the indoor unit is running but the outdoor unit is silent, you likely have a control or capacitor failure. If both are running and the air is cool, you are looking at a refrigerant charge issue or a reversing valve that has stuck in cooling mode. Both need a technician with gauges and a multimeter.
We also see this in neighboring towns with the same housing stock and the same weather swings. Homeowners searching for HVAC Vienna VA often describe the exact same symptoms, because the equipment and the climate are nearly identical.
Heat Pump Not Cooling Near Me Fairfax VA
Heat pump not cooling near me Fairfax VA is the summer version of the same problem, and it usually shows up as air that is cool but not cold, or a system that runs all day and never reaches the setpoint. In cooling mode, supply air should be 15°F to 20°F below the return air temperature. If it is only 5°F below, the system is losing capacity.
The three most common causes we find in Fairfax in July and August are a dirty outdoor coil, a failed run capacitor on the compressor, and low refrigerant from a slow leak. A dirty coil alone can cut capacity by 20% to 30%, which is enough to make a house that used to cool to 72°F struggle to hold 78°F.
If your system is more than 12 years old and you are facing a compressor replacement, the math often favors a new unit. Our AC replacement Fairfax VA page walks through what that decision looks like in practice, including typical 2026 pricing in this area.
Heat Pump Not Turning On Repair Fairfax VA
Heat pump not turning on repair Fairfax VA starts at the thermostat and works outward. If nothing happens when you call for heat or cool, the problem is almost always one of five things: a tripped breaker, a blown low-voltage fuse at the air handler, a failed contactor, a bad thermostat, or a float switch that has shut the system down because the condensate drain is clogged.
Before you call, check the breaker at the main panel and the disconnect box next to the outdoor unit. If the breaker trips again within a minute of resetting, stop and call us. A breaker that trips twice is a short, not a nuisance.
If the thermostat is blank, replace the batteries and check the low-voltage fuse on the control board. That fuse is a 3-amp or 5-amp automotive-style fuse, and it costs about $2. If it blows again after replacement, you have a wiring or transformer problem that needs a technician.
Common Mistakes to Watch Out For
The single most expensive mistake we see is homeowners running a heat pump in emergency heat mode for weeks because the system "still works." Emergency heat uses electric resistance strips, which cost roughly two to three times more per hour to run than the heat pump itself. A $400 repair can turn into a $900 electric bill in one cold month.
Other mistakes that cost real money:
- Adding refrigerant without finding the leak. A system that is low on charge has a leak. Topping it off buys you a season at best.
- Replacing the thermostat first. Thermostats fail far less often than capacitors and contactors. Diagnose before you buy.
- Ignoring a noisy outdoor fan. A fan motor that is grinding will eventually seize and take the compressor with it.
- Skipping the fall tune-up. A $99 to $149 tune-up in October catches most of the failures that would otherwise show up in January.
Regular HVAC maintenance Fairfax VA is the cheapest insurance you can buy on a heat pump. We clean the coils, check the charge, test the capacitors, and verify the defrost cycle before the heating season starts.
When to Call a Professional
Call a professional the moment you see ice that will not clear, a breaker that trips twice, or a system that has been running in emergency heat for more than a day. Those three symptoms point to problems that get worse, not better, with time.
Our technicians carry gauges, leak detectors, and replacement capacitors on the truck, so most heat pump repairs in Fairfax are done in a single visit. We diagnose first, tell you what it costs before we start, and fix the actual cause rather than the symptom.
If you are in one of the older neighborhoods where the housing stock dates to the 1960s and 1970s, we also work on the ductwork and electrical panels that feed these systems. Homeowners looking for HVAC Fairfax Station VA get the same service and the same upfront pricing.
Frequently Asked Questions
Why is my heat pump not working in Fairfax VA?
The most common causes in this area are a failed run capacitor, low refrigerant from a slow leak, a stuck reversing valve, and a defrost board that has stopped cycling. Airflow problems from a dirty filter or coil are close behind. Any of these will show up as weak heating, weak cooling, or short cycling.
What are signs I need heat pump repair in Fairfax VA?
Short cycling under 5 minutes, ice that stays on the outdoor coil after defrost, supply air that is only 5°F to 10°F above room temperature, grinding noises at startup, and electric bills that jump 20% or more with no change in use. Two or more of these together means it is time to call.
How do I fix a heat pump that is not heating in Fairfax VA?
Check the thermostat mode, confirm the outdoor unit is running, and clear any leaves or ice from the coil. If the outdoor unit is silent or the air stays cool after 10 minutes, the fix is a technician-level repair. Capacitors, reversing valves, and refrigerant charge all require test instruments.
Should I call an HVAC technician in Fairfax VA for heat pump not working?
Yes, if the symptom has repeated for more than one cycle or you have been without heat or cooling for over four hours. A single hiccup on a cold morning can be normal defrost behavior. Anything that repeats is a repair, and waiting usually makes it more expensive.
How much does heat pump repair cost in Fairfax VA in 2026?
Most single-visit repairs in this area run $250 to $650, covering the diagnostic, the part, and labor. Capacitors and contactors sit at the low end. Blower motors, reversing valves, and refrigerant leak repairs sit at the high end. Compressor replacements start around $1,400 and are often better put toward a new system.
Get Help with HVAC in Fairfax
If your heat pump is short cycling, blowing cold air, or refusing to start, we can diagnose it and give you a straight answer on whether it is a repair or a replacement. Call Fairfax HVAC Experts at +15717604715 and we will get your system back to doing its job.