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A5

Error A5 (10 Green, 5 Red Flashes) — Low pressure abnormal

Fujitsu · Air to Water Heat Pumps

What does A5 mean?

The hydraulic unit's green LED flashes ten times and the red LED flashes five times. This indicates an abnormally low pressure condition in the system.

Common Causes

  • Insufficient refrigerant charge (leakage).
  • Blockage or restriction in the refrigerant line.
  • Faulty low-pressure sensor or switch.
  • Outdoor unit operating in extremely cold temperatures without proper protection.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Power cycle the heat pump system by turning off the main breaker for 60 seconds and then restoring power.

  2. 2

    Check the outdoor unit for signs of ice formation on refrigerant lines, which could indicate low refrigerant.

  3. 3

    Ensure the outdoor unit is free from obstructions and has proper airflow.

  4. 4

    If the error persists, contact a qualified technician to check refrigerant levels and diagnose the low-pressure circuit.

Browse all codes in this manual (59)
Verified technical data. Last updated: April 2026

Related Faults

1 Flash (Outdoor Unit)Outdoor Unit LED 1 Flash — Serial forward transfer error10Fault 10 — Outdoor sensor error11Error 11 (1 Green, 1 Red Flash) — Communication error between Hydraulic and Outdoor unit
Source: Fujitsu Air to Water Heat Pumps
Open Manual (Page 6)Search more codes in this manual