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Carrier · Heat pump troubleshooting

Outdoor unit will not run - HK32EA defrost board heat pumps

What is going on

Thermostat calls but the outdoor unit stays off on heat pumps with HK32EA defrost boards.

Likely causes

  • No Y signal from thermostat
  • Open pressure switch
  • 5-minute delay still timing (003/008)
  • Failed contactor
  • Capacitor or compressor fault

Check in this order

  1. Measure 24 V at the Y input; none means thermostat or wiring.
  2. Check 24 V on the board Y spade; this feeds the pressure switches and returns to T1.
  3. On 003/008 boards the time delay may be active: short the speed-up pins for no more than 1 s to skip it.
  4. Look for 24 V at the contactor coil from T2; none points to an open pressure switch.
  5. Coil has 24 V but contactor open: replace the contactor.
  6. Contactor closed but nothing runs check wiring, capacitor and compressor.

Applies to: Carrier/Bryant single-stage heat pumps with HK32EA001/007/003/008/009/010/011

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Source: Carrier Residential AC & HP Application Guideline and Service Manual 24-25-9SM (text export), Troubleshooting (HK32EA001/007 and 003/008). 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.