Daikin Chiller

Daikin Chiller Error Code H4

Troubleshooting guide for the Daikin Chiller system fault H4.

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What It Means

Malfunction of low pressure switch (LPS).

Possible Causes

  • Defective low pressure switch.
  • Broken wire.
  • Defective outdoor unit PCB.
  • Defective connector contact.

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 switch (LPS)

All Recorded Causes

Defective low pressure switch Broken wire Defective outdoor unit PCB Defective connector contact

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 low pressure switch.
  3. Look for restrictions, iced coils, or dirty heat-transfer surfaces that can mimic a charge problem, and separately confirm broken wire.
  4. After the correction, run the system long enough to confirm the chiller fault does not return under normal load.

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