Daikin SkyAir

Daikin SkyAir Error Code J9

Troubleshooting guide for the Daikin SkyAir system fault J9.

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What It Means

Malfunction of thermistor (Refrigerant circuit).

Possible Causes

  • Defective connection of thermistor.
  • Defective gas pipe thermistor.
  • Defective outdoor unit PCB.

Not sure which one it is — or if it's none of these? Try ACLogics today.

Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis

Malfunction of thermistor (Refrigerant circuit)

All Recorded Causes

Defective connection of thermistor Defective gas pipe thermistor Defective outdoor unit PCB

Verify Before Replacing Parts

  1. Confirm the exact Daikin model family and skyair context before acting on a generic code description.
  2. Verify airflow first, then confirm operating pressures and temperature relationship before adjusting charge, since defective connection of thermistor.
  3. Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm defective gas pipe thermistor.
  4. After the correction, run the system long enough to confirm the skyair fault does not return under normal load.

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