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AA-01

AA-01 — Backup heater overheated or BUH power cable not connected

Daikin · ASHP Error Codes

What does AA-01 mean?

The backup heater has overheated, or its power cable is not properly connected.

Common Causes

  • Faulty thermostat for backup heater
  • Wiring issue
  • Backup heater element failure

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Check that the BUH power cable is securely connected.

  2. 2

    Inspect the backup heater for any visible damage.

  3. 3

    Reset the unit via the power supply.

  4. 4

    If the problem persists, a technician should inspect the backup heater.

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

Related Faults

7H-017H-01 — Water flow problem7H-047H-04 — Water flow problem during domestic hot water production7H-057H-05 — Water flow problem during heating/sampling
Source: Daikin ASHP Error Codes
Open Manual (Page 2)Search more codes in this manual