If your heat pump is running but the air coming out of the vents is cool, or the outdoor unit is humming and nothing happens inside, the most likely culprits are a stuck reversing valve, a failed defrost board, a low refrigerant charge, or a thermostat still set to cool. In Poway, where winter nights routinely drop into the low 40s and summer afternoons hit 95°F, we see all four every week. Below we walk through the eight causes we actually find on Poway rooftops, what each repair costs in 2026, and the checks you can safely do yourself before you call anyone.
The short answer: why your Poway heat pump is not heating
A heat pump not heating in Poway CA is almost always one of three things: the system is stuck in cooling mode (reversing valve or thermostat), it is frozen over and locked out on defrost, or it has lost refrigerant and cannot move heat indoors. Those three account for roughly 8 out of every 10 no-heat calls we run in this city.
Here is the definition worth keeping in your head: a heat pump is a reversible refrigeration system that moves heat from outdoor air into your house in winter and reverses the flow in summer. There is no flame and no gas burner. If any part of that reversal or refrigerant loop fails, you get a fan blowing room-temperature air instead of heat.
Poway homes make this worse in specific ways. Most of the housing stock here was built between 1975 and 2005, so we are working on 20- to 50-year-old electrical panels, aging contactors, and ductwork that has been baking in an attic that hits 140°F every August. That heat cycling is hard on capacitors and control boards.
Why is my heat pump not heating in Poway CA? The 8 causes we find most
1. The reversing valve is stuck in cooling mode
The reversing valve is the part that flips your system between heating and cooling. When it sticks, the outdoor unit runs, the indoor fan runs, and you get cold air in January. You will usually hear a faint hiss or a click that never quite finishes when you switch modes at the thermostat.
This is the single most common no-heat failure we diagnose in Poway. A Heat Pump Reversing Valve Repair Poway CA runs $450 to $900 in 2026 including the valve, the refrigerant recovery, and the recharge. It is not a DIY job - the valve sits inside the refrigerant circuit and requires brazing and a vacuum pull.
2. The defrost board has failed and the coil is iced over
In heating mode your outdoor coil gets cold - colder than the air around it - so frost forms. The defrost board is supposed to run a short reverse cycle every 30 to 90 minutes to melt it off. When that board dies, the coil turns into a solid block of ice and the system stops transferring heat.
Look at the outdoor unit. If you see a sheet of white frost covering more than half the coil, and it is still there 20 minutes after you shut the system off at the thermostat, the defrost cycle is not running. A Heat Pump Defrost Board Repair Poway CA is typically $350 to $700.
3. Low refrigerant from a slow leak
Refrigerant does not get used up. If your charge is low, you have a leak - usually at a Schrader valve, a brazed joint, or the coil itself. Symptoms are a system that heats weakly, runs constantly, and never quite reaches the setpoint on the thermostat.
We pressure-test, find the leak, and repair it rather than just topping off the charge. A Heat Pump Refrigerant Leak Repair Poway CA runs $400 to $1,100 depending on whether we are repairing a joint or replacing a coil. Topping off without finding the leak is money you will spend again next winter.
4. The thermostat is set wrong or wired wrong
Heat pumps need a heat pump thermostat. A standard thermostat will call for heat, the system will run, and the auxiliary heat will never stage in - or worse, the thermostat will energize the reversing valve on the wrong cycle and you get cool air on a heat call.
Check the mode first. Then check whether the thermostat has a heat pump setting enabled. If it does and you still get cold air, a Heat Pump Thermostat Repair Poway CA is a $180 to $420 fix, and it is one of the fastest diagnostics we run.
5. A failed capacitor or contactor
Your compressor and outdoor fan both need a run capacitor to start and stay running. Poway attic and rooftop temperatures kill capacitors fast - we replace more of them here between June and September than any other single part.
If you hear a click from the outdoor unit and then nothing, or the fan spins slowly and the compressor never kicks in, that is the tell. A Heat Pump Capacitor Replacement Poway CA is $150 to $320, and a Heat Pump Contactor Replacement Poway CA is $180 to $400. Both are same-visit repairs.
6. The blower motor is dying
If the outdoor unit is running and warm but you feel almost no airflow at the vents, the indoor blower is the problem. A failing blower motor will sometimes run at half speed for weeks before it quits entirely. You may also hear a grinding or squealing from the air handler.
A Heat Pump Blower Motor Repair Poway CA is $400 to $850 depending on whether we replace just the motor or the whole blower assembly.
7. Auxiliary heat never engages
Heat pumps are sized to heat a house down to a balance point - usually around 35°F to 40°F in Poway. Below that, the system needs the electric resistance strips (auxiliary or emergency heat) to keep up. If the sequencer, relay, or control board that stages those strips has failed, the house will slowly lose ground on cold nights even though the heat pump itself is fine.
We test the strip circuit and the staging controls together. A Heat Pump Relay Replacement Poway CA or control board fix is $250 to $650.
8. The system is locked out on a safety fault
Modern heat pumps shut themselves down when they detect a high-pressure, low-pressure, or discharge-temperature fault. The unit looks dead but it is protecting itself. The fault code is stored in the control board and we read it before we touch anything else.
If you are seeing a code on the board or a blinking LED pattern, note the pattern before you power anything down. That code saves us 20 minutes on the diagnostic and saves you the cost of that time.
Heat pump not heating in cold weather Poway CA: what is normal
Poway winters are mild - overnight lows in the low 40s, with a handful of nights that dip to 32°F or just below. A properly sized and charged heat pump should heat your house comfortably down to about 35°F without auxiliary heat. Below that, the strips stage in and you will see the thermostat display "aux heat" or "emergency heat."
What is not normal: the system running 100% of the time and the house still dropping. That is a capacity or charge problem, not a weather problem. If it happens every night in January, you have a repair to make, not a thermostat to adjust.
One more Poway-specific note. Homes in the older parts of town, including the heat pump repair in Old Poway CA area, often have original 1970s and 1980s ductwork. Leaky ducts in a Poway attic can lose 20% to 30% of your heat before it reaches the register. If your heat pump is running perfectly and the rooms are still cold, get the ducts checked.
How do I troubleshoot a heat pump not heating in Poway California?
You can safely check five things in about ten minutes. Anything past that involves the refrigerant circuit or line voltage and belongs to a licensed technician.
- Confirm the thermostat is in HEAT mode and set at least 3°F above the current room temperature. Heat pumps have a small delay before the indoor fan starts - give it 5 minutes.
- Check the air filter. A clogged filter restricts airflow and can trip a high-limit safety. Replace it if you cannot see light through it.
- Look at the outdoor unit. If it is buried in frost or ice, shut the system off at the thermostat and let it thaw for an hour. If it re-ices within a day, the defrost cycle is failing.
- Check the breaker at your panel and the disconnect box next to the outdoor unit. Heat pumps often have two breakers - one for the indoor air handler and one for the outdoor condenser.
- Listen at the outdoor unit. A click with no follow-up hum points to a capacitor or contactor. A hum with no fan points to the fan motor.
If all five check out and you still have cold air, stop. The next step is a set of gauges and a multimeter, and that is where we come in. If you want a full system review before winter, a Heat Pump Tune-Up Poway CA catches most of these failures before they strand you on a cold night.
What a heat pump not heating repair costs in Poway in 2026
Typical 2026 pricing in this area breaks down like this. These are the ranges we quote before we start work, and we tell you the number before we open the panel.
- Diagnostic visit: $89 to $149, applied to the repair if you approve it.
- Capacitor or contactor: $150 to $400 parts and labor.
- Thermostat replacement: $180 to $420.
- Defrost board: $350 to $700.
- Blower motor: $400 to $850.
- Reversing valve: $450 to $900.
- Refrigerant leak repair: $400 to $1,100.
- Compressor replacement: $1,400 to $2,600.
If the compressor has failed and the unit is 12 years or older, replacement usually beats repair. A Heat Pump Replacement Poway CA runs $6,500 to $12,000 installed in 2026 depending on tonnage, SEER2 rating, and whether we are reusing the existing line set and ductwork.
Common mistakes Poway homeowners make
The most expensive mistake is running the system while it is iced over. You will slug liquid refrigerant back to the compressor and turn a $500 defrost board repair into a $2,000 compressor replacement. Shut it off at the thermostat and let it thaw.
The second is adding refrigerant without finding the leak. It works for a season and then you are back where you started, minus the cost of the charge.
The third is replacing the thermostat first because it is the cheapest part. We see this constantly. If the thermostat is not the problem, you have spent $250 and you still have cold air.
The fourth is ignoring the auxiliary heat strips. Homeowners assume the heat pump is failing when the strips are the part that quit. Test both circuits before you decide what to replace.
And the fifth: letting a failing system limp through December because the days are still warm. Poway afternoons hit 70°F in early winter, so a weak heat pump feels fine at 2 p.m. and fails at 6 a.m. Fix it in November, not on the coldest night of the year.
When to call a professional
Call us when the outdoor unit is iced over and will not clear, when you smell burning at the air handler, when the breaker trips more than once, or when you have cold air and the thermostat is confirmed in heat mode. Those four situations cover every refrigerant, electrical, and control-board failure on the list above.
Pump Repair Pros handles heat pump diagnostics and repair across Poway, including same-day service on most no-heat calls. We test the reversing valve, the defrost circuit, the refrigerant charge, and the auxiliary heat staging in one visit, so you get a real answer instead of a guess. If you would rather not wait, our Emergency Heat Pump Repair Poway CA line is staffed around the clock.
Frequently Asked Questions
Why is my heat pump not heating in Poway CA?
In Poway, the four most common causes are a reversing valve stuck in cooling mode, a failed defrost board that leaves the coil iced, a low refrigerant charge from a leak, and a thermostat not configured for heat pump operation. Together these account for about 8 out of 10 no-heat calls we run here.
How do I troubleshoot a heat pump not heating in Poway California?
Check five things in order: thermostat in HEAT mode and set 3°F above room temp, clean air filter, outdoor unit free of frost, both breakers on, and listen for a click-hum at the outdoor unit. If all five are fine and you still have cold air, it is a refrigerant or control fault and needs gauges.
What causes a heat pump to not heat in Poway CA?
Beyond the big four, we find failed run capacitors, worn contactors, dying blower motors, auxiliary heat strips that never stage in, and control-board safety lockouts. Poway attic heat accelerates capacitor and board failures, which is why we replace more of them here than in cooler coastal areas.
Can I fix my heat pump not heating myself in Poway?
You can safely reset breakers, change the filter, switch the thermostat mode, and thaw a frosted outdoor coil. You cannot legally or safely handle refrigerant, brazing, or line-voltage control wiring without a licence. Anything past the five checks above belongs to a technician.
Who repairs heat pumps not heating near me in Poway?
Pump Repair Pros repairs heat pumps not heating across Poway, including Old Poway, Rancho Arbolitos, and the Poway Road corridor. We run diagnostics on the reversing valve, defrost board, refrigerant charge, and auxiliary heat circuit in one visit, and most no-heat calls are fixed same day.
Get help with Heat Pump Repair in Poway
Cold air from a heat pump is a fixable problem, and in most Poway homes it is a same-day fix. Call Pump Repair Pros at (111) 222 3333 and we will diagnose the reversing valve, defrost circuit, refrigerant charge, and auxiliary heat in one visit.
We quote the repair before we start, we carry the common Poway parts on the truck, and we test the system in heat mode before we leave your driveway.