ErrorCodeDoctor
Daikin · Air Conditioner

Daikin Air Conditioner U3 error code

Difficulty: Medium · Cost: $0–$150 · Duration: 10–20m

The U3 code means the check operation has not been executed on your Daikin air conditioner. The check operation is a required commissioning step that must be performed after installation or a PCB replacement before normal operation can begin. Run the check operation using the remote controller following the instructions in the installation manual. This applies to all Daikin system types.

Common causes

  • Check operation has not been performed after installation
  • Check operation was not run after a PCB replacement

How to fix it

  1. 1

    Run the check operation on the remote controller following the instructions in the installation or service manual

  2. 2

    If the check operation was performed but U3 still appears contact a qualified technician to inspect the transmission wiring

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