ErrorCodeDoctor
Daikin · Air Conditioner

Daikin Air Conditioner H9 error code

Difficulty: Hard · Cost: $80–$250 · Duration: Requires professional service

The H9 error means your Daikin air conditioner detected a fault with the outdoor air thermistor — the sensor that measures the outside air temperature. Without this reading the unit cannot optimise its operation for ambient conditions. Contact a qualified technician to test and replace the outdoor air thermistor.

Common causes

  • Outdoor air thermistor connector is loose or disconnected
  • Outdoor air thermistor is defective
  • Outdoor unit PCB has a fault

How to fix it

  1. 1

    Contact a qualified technician to inspect and replace the outdoor air thermistor

Related Daikin Air Conditioner error codes

1

A0

An external protection device connected to the indoor unit has been activated

hard
2

A1

A fault was detected in the indoor unit PCB (control board)

hard
3

A3

The drain level control system has detected an abnormality — drain may be clogged

medium
4

A5

Freeze-up protection (cooling) or high pressure control (heating) has activated — check the air filter

easy