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H9

H9 - Failed ambient sensor

Daikin · Air Conditioning

What does H9 mean?

The sensor measuring the outside ambient temperature has failed (open or short circuit).

Common Causes

  • Ambient sensor open or short circuit.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Locate the ambient sensor on the outdoor unit and check its connection.

  2. 2

    Inspect the sensor and its wiring for any visible damage.

  3. 3

    If the sensor or wiring is faulty, it must be replaced by a qualified technician.

Browse all codes in this manual (79)
Verified technical data. Last updated: April 2026

Related Faults

A0A0 - External protection activeA1A1 - Indoor PCB failureA2A2 - Malfunction of freezing protection
Source: Daikin Air Conditioning
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