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H4

H4 - Actuation of low pressure switch (LPS) (Outdoor Unit)

Daikin · Simple Self Diagnosis by Malfunction Code | Daikin

What does H4 mean?

The low-pressure switch in the outdoor unit has activated, signaling critically low refrigerant pressure.

Common Causes

  • Low refrigerant charge
  • Refrigerant leak
  • Blockage in refrigerant lines
  • Faulty LPS

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Turn off the unit.

  2. 2

    Check that all air intakes and filters are clear.

  3. 3

    Restore power.

  4. 4

    If the error persists, a refrigerant leak check by a professional is necessary.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

6-06-0 - External protection device activated (Heat reclaim ventilator)6-16-1 - Malfunction of PCB (Heat reclaim ventilator)6-26-2 - Ozone density abnormal (Heat reclaim ventilator)
Source: Simple Self Diagnosis by Malfunction Code | Daikin
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