York Heat Pump Not Heating: Causes, Fixes & Costs
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York heat pump not heating: what it means
“Not heating” is a symptom, not a stored fault code. Your York heat pump is running but delivering cool or barely warm air, or the outdoor unit isn’t running when the thermostat calls for heat.
Many York outdoor units have a control board with a diagnostic LED. That LED may show a specific fault, such as a pressure-switch trip or a defrost or sensor problem. Flash meanings differ by board, so read them against the chart on your unit’s access panel rather than a generic list.
Whether it resets: Many York heat pump controls retry automatically after a built-in delay of roughly 5 minutes. Repeated pressure-switch trips can lock the compressor out until power is cycled. This behavior varies by board.
Heat pump vs. furnace: This page covers the heat pump side. If your York system is dual-fuel and the gas furnace is the part that won’t heat, see the furnace pages listed under Related codes.
York heat pump not heating: common causes, ranked by probability
- Thermostat set up wrong or failing. Common versions include:
- The thermostat is in Cool or Off mode.
- It is configured for a conventional system instead of a heat pump.
- The O/B reversing-valve setting is wrong. York heat pumps typically energize the reversing valve in cooling (O).
- The batteries are dead.
- Normal defrost cycle or normal low supply temperature. During defrost the unit briefly blows cooler air and the outdoor unit may steam. Heat pumps also deliver cooler air than furnaces.
- Dirty air filter or blocked airflow. Restricted indoor airflow cuts capacity. It can also trip the high-pressure switch in heating mode.
- Outdoor unit power off. A tripped breaker or a pulled disconnect at the outdoor unit stops heating while the indoor blower keeps running.
- Outdoor coil iced over or defrost failure. A faulty defrost control, a bad coil or ambient sensor, or a failed defrost relay can leave the coil blocked by ice.
- Low refrigerant charge (leak). A leak reduces heating capacity and can trip the low-pressure switch.
- Reversing valve stuck or its solenoid failed. The unit stays in cooling mode and blows cold air with a heating call.
- Failed run capacitor or contactor. The compressor or outdoor fan won’t start or hums.
- Auxiliary or backup heat failure. Burned-out heat strips, a failed sequencer, or a heat-kit breaker can cause problems. This mainly shows up in very cold weather, when the heat pump alone can’t keep up.
- Compressor failure. This is the least likely cause and the most expensive.
How to fix York heat pump not heating: safe checks first
- Thermostat: Confirm it is set to Heat, with the setpoint at least 3°F above room temperature. Replace the batteries. If you recently installed a new thermostat, confirm it is set to “heat pump” in its installer menu. If you’re unsure about the O/B setting, leave it to a tech.
- Air filter: Replace it if it is dirty. Then check that the supply registers are open and the return grilles aren’t blocked by furniture.
- Breakers: Check the breakers for the indoor air handler, the outdoor unit, and any separate heat-strip breaker. Reset a tripped breaker once. If it trips again, stop and call a technician.
- Outdoor disconnect: Confirm the disconnect switch or pull-out block near the outdoor unit is fully seated and on.
- Outdoor unit clearance: Clear snow, leaves, and debris from around the unit and off the top. Keep about 2 feet of clearance. Do not chip or pry ice off the coil, and do not pour hot water on it.
- Wait out a defrost: If the outdoor unit is steaming or the fan is stopped, wait 10–15 minutes and see whether heat returns.
- Condensate: Check that the indoor drain line isn’t clogged and the drain pan or float switch isn’t full. A tripped float switch can shut the system off.
- Access panels: Make sure the indoor unit’s access panels are fully seated.
- One reset: Turn the thermostat off, switch off power at the breakers for 5 minutes, then restore power. Do this once. If the problem repeats, stop resetting and call a pro.
- Emergency heat: Use Emergency or Aux heat to stay warm until service arrives.
How a technician will diagnose it
A qualified tech will typically work through these steps:
- Confirm the heating call. Verify the thermostat signals with a meter at the outdoor control: Y, O/B, and W.
- Read the outdoor board’s diagnostic LED. They will check it against the model-specific chart.
- Measure temperature split. They check the temperature difference across the indoor coil and confirm the outdoor unit is actually running.
- Test electrical components. This includes the contactor, the run capacitor (microfarad reading), voltage at the compressor, and compressor winding resistance.
- Check the reversing valve. They test the solenoid’s coil voltage and resistance and compare line temperatures to see whether the valve shifts.
- Measure refrigerant pressures. They connect gauges and calculate superheat and subcooling against York’s charging chart. If the charge is low, they should leak-search before recharging.
- Check defrost. They test the defrost control, the coil and ambient sensors, and the defrost logic.
- Check backup heat. They test the heat strips, sequencers, and limits if supplemental heat is part of the complaint.
A good quote names the failed part and the measurement that proved it. Be wary of “just add refrigerant” without a leak search.
Symptom, cause and what to do
| Symptom | Likely cause | DIY action | Technician job |
|---|---|---|---|
| Cold air, outdoor unit off | Breaker or disconnect off, thermostat mode wrong | Check thermostat mode, reset breaker once, check disconnect | Test contactor, capacitor, control voltage |
| Cold air, outdoor unit running | Reversing valve stuck or O/B misconfigured | Confirm thermostat is set to heat pump and Heat mode | Test solenoid, verify valve shift, correct O/B wiring |
| Brief cool air, steam from outdoor unit | Normal defrost | Wait 10–15 min | None if heat returns |
| Outdoor coil solid with ice | Defrost control or sensor failure, low charge | Clear debris, use Emergency heat | Test defrost board and sensors, check charge |
| Weak heat, long run times | Dirty filter, low refrigerant | Replace filter, open registers | Pressure and superheat test, leak search and repair |
| Outdoor unit hums, won’t start | Failed capacitor or compressor issue | Shut off at breaker, call pro | Replace capacitor or contactor, test compressor |
| Heat OK when mild, not when very cold | Backup heat strips or sequencer failed | Check heat-strip breaker once | Test strips, sequencer, limits |
| System dead, drain pan full | Condensate float switch tripped | Clear the drain line | Clean drain, check float switch |
York heat pump not heating repair cost
Typical US ranges, parts and labor:
| Repair | Typical cost |
|---|---|
| Thermostat batteries, filter, breaker reset | $0–$40 DIY |
| Service call and diagnosis | $90–$200 |
| Thermostat replacement and setup | $150–$450 |
| Run capacitor | $150–$400 |
| Contactor | $150–$350 |
| Defrost control board | $300–$700 |
| Coil or ambient sensor | $150–$350 |
| Heat strip or sequencer | $200–$600 |
| Leak search and repair, plus recharge | $400–$1,500+ (depends on leak location and refrigerant type) |
| Reversing valve replacement | $1,000–$2,500 |
| Compressor replacement | $1,800–$3,500+ (often weighed against full replacement) |
Check your York warranty before paying for major parts. Many units carry 10-year parts coverage if they were registered.
Related codes
- York Furnace Blowing Cold Air: Causes, Fixes & Costs
- York Furnace Runs Constantly But Not Enough Heat: Fixes
- York Furnace Won’t Turn On: Causes, Fixes & Costs
- York Furnace Blower Not Running: Causes & Fixes
- York Furnace Leaking Water: Causes, Fixes & Costs
Parts & tools for this fix
- Replacement HVAC air filter (match your size)
- AA/AAA thermostat batteries
- Heat pump compatible programmable thermostat
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Frequently asked questions
Is it normal for my York heat pump to blow lukewarm air?
Yes, to a degree. Heat pump supply air is often only 85–100°F, which feels cool compared with a furnace. If the air is near room temperature or the house keeps losing ground, something is wrong.
Why is steam coming from my outdoor unit and the heat stopped?
That is usually a normal defrost cycle. The unit briefly reverses to melt frost off the outdoor coil. It typically lasts a few minutes, up to about 10, then heating resumes. A unit that stays encased in ice needs a technician.
Can I just switch to emergency heat?
Yes. Emergency or auxiliary heat runs the backup electric strips or furnace and keeps you warm while you wait for service. It costs much more to run, so schedule the repair promptly.
Does a York heat pump fault reset itself?
It depends on the model and board. Many outdoor controls retry automatically after a short anti-short-cycle delay. Some protections, such as repeated high- or low-pressure trips, can latch until power is cycled. Reset power once only, and call a pro if the problem returns.
Could low refrigerant cause no heat?
Yes. A leak reduces capacity and can trip the low-pressure switch, which shuts down the compressor. Refrigerant work requires an EPA-certified technician, who should find and repair the leak rather than just add refrigerant.