York Heat Pump Not Cooling: Causes, Fixes & Costs

Last updated Oct 5, 2026 · By fixme.vip Editorial

York heat pump not cooling: what it means

“Not cooling” is a symptom, not a numbered fault code. Your York heat pump either won’t run in cooling mode or runs without bringing the indoor temperature down.

A heat pump cools by shifting its reversing valve into cooling position. On most York systems, the thermostat energizes the O terminal to do this. The compressor then pumps refrigerant to pull heat out of the house.

Cooling fails when any link in that chain breaks:

• the thermostat call
• the reversing valve
• outdoor unit power and starting components
• refrigerant charge
• airflow across the coils

Some York units with a fault-LED defrost board, or variable-speed/communicating models such as systems using the Affinity Hx communicating thermostat, may show a stored fault code. One example is a high- or low-pressure switch lockout. LED meanings differ by board, so read the label inside the outdoor unit’s control panel cover. A technician can do this, or you can find it in the installation manual.

Pressure-switch lockouts on some York boards clear automatically after a delay. Others hold until power is cycled. Cycle power no more than once. If it locks out again, call a technician.

York heat pump not cooling: common causes, ranked by probability

1. Thermostat setting or configuration. The thermostat may be set to Heat or Auto, or the setpoint may sit above room temperature. On a newly installed thermostat, the reversing-valve setting may be wrong. York normally uses O, energized in cooling. If it is set to B, the unit heats when you ask for cooling.
2. Dirty air filter or blocked airflow. Restricted airflow can freeze the indoor coil, and cooling drops off sharply. Closed registers and blocked returns cause the same problem.
3. Dirty or blocked outdoor coil. Cottonwood, grass clippings, leaves or nearby shrubs keep the unit from rejecting heat. Head pressure rises and the high-pressure switch may trip.
4. Failed run capacitor or contactor in the outdoor unit. The outdoor fan or compressor won’t start, or the unit hums. This is one of the most common outdoor-unit failures on any brand. In field service calls, the capacitor is often the top hardware failure behind a no-cool complaint. It sits below causes 1–3 here only because those are simpler problems you can check yourself first.
5. Low refrigerant from a leak. You may notice long run times, an iced suction line or poor temperature drop. Evaporator coil leaks from corrosion are common on older units of all brands. If a coil leak is found, check whether your coil is still under York’s registered parts warranty.
6. Reversing valve stuck in heating position, or a failed solenoid coil. The outdoor unit runs, but the house gets warmer.
7. Outdoor fan motor failure. The compressor runs but the fan doesn’t. High pressure builds until the unit trips.
8. Pressure switch trip or control board fault. This shows on fault-LED boards. It can be triggered by any of causes 3–7, or by a failed switch or board.
9. Compressor failure. This is the least likely cause and the most expensive. Signs include a locked rotor, an open winding or an internal overload that won’t reset.

How to fix York heat pump not cooling: safe checks first

• Thermostat: Set it to Cool, not Auto. Set the temperature at least 3°F below room temperature, and make sure the fan is on Auto. Replace the batteries if the display is dim or blank.
• Wait out the delay: After any change, wait 5–10 minutes. York boards commonly hold the compressor off for a few minutes to protect it.
• Air filter: Replace the filter if it is dirty.
  • If the indoor coil or refrigerant lines are iced, turn the system to Off.
  • Run the fan On for a few hours to thaw the coil before trying Cool again.
• Breakers and disconnect: Check the indoor and outdoor breakers. Make sure the outdoor disconnect switch or pull-out next to the unit is fully seated. Reset a tripped breaker once only. If it trips again, stop and call a technician.
• One reset: If you suspect a lockout, turn the thermostat off and switch off power at the breaker for 5 minutes. Then restore power and try Cool once.
• Outdoor clearance: From outside, without opening the unit, clear away leaves and debris. Trim plants back to about 2 feet of clearance. You can gently hose the fins from the outside with the power off.
• Vents and returns: Open the supply registers and make sure nothing blocks the return grilles.
• Condensate: Some indoor units have a float switch that cuts cooling when the drain backs up. Check that the condensate line is draining at its outlet. Clear a visible clog at the drain opening, or pour a cup of distilled vinegar into the access port if your unit has one.
• Panels: Make sure the indoor unit’s access panels are seated properly.

Do not open the outdoor unit’s electrical panel. It holds high voltage, and capacitors stay charged even with the power off.

How a technician will diagnose it

A competent technician will typically work through these steps:

1. Verify the thermostat call. They check for 24 V on Y and O at the outdoor unit and confirm the thermostat’s O/B configuration.
2. Read the board. They check any fault LED or stored code on the defrost or control board, or pull the history on communicating York controls.
3. Check power and start components. They measure line voltage at the contactor, inspect the contactor points and test the dual run capacitor with a meter against its µF rating.
4. Check the fan and compressor. They confirm the outdoor fan motor runs and measure compressor amp draw and winding resistance.
5. Measure the refrigerant system. They attach gauges or probes and record suction and liquid pressures, superheat and subcooling. These numbers are compared with York’s charging chart for the specific model and metering device (TXV or piston).
6. Test the reversing valve. They check the temperatures on the valve’s lines and test the solenoid coil for voltage and resistance.
7. Measure airflow and temperature split. They measure the supply and return temperature difference (about 15–20°F is typical) and static pressure. They also inspect the indoor coil for dirt or ice.
8. Find leaks if the charge is low. They use an electronic detector, bubble solution or a nitrogen pressure test before recharging.

Be cautious of a quote that recommends a refrigerant top-off without measurements or any mention of finding the leak. Be equally cautious of a compressor replacement quote issued before the capacitor and contactor were tested.

Symptom, cause and what to do

York heat pump not cooling repair cost

These are typical US installed prices. They vary by region, refrigerant type and warranty status. York parts warranties are often 5–10 years when the unit is registered, but labor usually isn’t covered.

On an older system, a compressor or coil replacement often makes replacing the whole heat pump worth comparing. A new system typically runs $5,000–$12,000.

Related codes

York Heat Pump Not Heating: Causes, Fixes & Costs covers heating-mode failures, defrost problems and the reversing valve from the heating side.

York Furnace Blower Not Running: Causes & Fixes applies when the indoor fan won’t run in cooling mode on a furnace-paired system.

York Furnace Leaking Water: Causes, Fixes & Costs covers condensate drain and float switch issues that can shut down cooling.

York Furnace Short Cycling: Causes, Diagnosis & Fixes covers thermostat and control cycling issues that overlap with cooling-side complaints.