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Goodman · Heat pump troubleshooting

No heat - R-32 GLZS/ALZS heat pump

What is going on

Heat pump does not deliver heat in heating mode.

Likely causes

  • Thermostat left in cool mode or wiring fault
  • Supply or transformer problem
  • Contactor, capacitor or compressor fault
  • Reversing valve stuck, mis-piped or getting 24 V on O in heat
  • Metering device fault
  • Indoor blower fault
  • Wrong charge

Check in this order

  1. Confirm the thermostat is in heat mode.
  2. Check 230 V to the unit and transformer, 24 V on Y and at the contactor coil (check pressure switches if missing).
  3. Contactor closed but compressor off check wiring, run capacitor, overload and windings; let a hot compressor cool before retesting.
  4. Compressor runs but no heat if the reversing valve is stuck between heat and cool, replace it; check for 24 V on O (it should not be energized in heat on legacy wiring).
  5. Check the reversing valve is piped correctly and the metering device works.
  6. Indoor blower off check 24 V on G, the blower relay/control wiring and the motor.
  7. Confirm charge with subcooling and superheat.

Applies to: R-32 GLZS4/5 and ALZS4/5 heat pumps

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Source: Goodman RS6200301 R-32 GLXS/ALXS/GLZS/ALZS service (07-2024), Heat Pump - Heating flowchart p.52-53. Written in our own words; check the manual for your exact model.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.