Daikin Chiller

Daikin Chiller Error Code J4

Troubleshooting guide for the Daikin Chiller system fault J4.

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What It Means

Malfunction of low pressure equivalent saturated temperature sensor system.

Possible Causes

  • Defective connection of thermistor.
  • Defective 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 low pressure equivalent saturated temperature sensor system

All Recorded Causes

Defective connection of thermistor Defective thermistor Defective outdoor unit PCB

Verify Before Replacing Parts

  1. Confirm the exact Daikin model family and chiller 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 thermistor.
  4. After the correction, run the system long enough to confirm the chiller fault does not return under normal load.

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