ErrorCodeDoctor
Daikin · Air Conditioner

Daikin Air Conditioner C9 error code

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

The C9 error means your Daikin air conditioner detected a fault with the suction air thermistor — the sensor that measures the temperature of the air being drawn into the indoor unit. Without an accurate suction air temperature reading the unit cannot control cooling or heating precisely. Contact a qualified technician.

Common causes

  • Suction air thermistor is defective
  • Indoor unit PCB has malfunctioned
  • Thermistor connector has a poor contact

How to fix it

  1. 1

    Contact a qualified technician to test and replace the suction 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