ErrorCodeDoctor
Daikin Air Conditioner U3 error code
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
Run the check operation on the remote controller following the instructions in the installation or service manual
-
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
A0
An external protection device connected to the indoor unit has been activated
A1
A fault was detected in the indoor unit PCB (control board)
A3
The drain level control system has detected an abnormality — drain may be clogged
A5
Freeze-up protection (cooling) or high pressure control (heating) has activated — check the air filter
U3 error — frequently asked questions
What does the U3 error mean on a Daikin air conditioner?
The check operation has not been executed — run it before normal operation
What causes the U3 error?
The U3 error is usually caused by: Check operation has not been performed after installation; Check operation was not run after a PCB replacement.
Can I fix the U3 error myself?
It's possible for a moderately handy person, but budget 10–20m and expect some disassembly.
How much does it cost to fix the U3 error?
Fixing the U3 error on a Daikin air conditioner typically costs $0–$150, depending on parts and whether you do it yourself or hire a technician.
Is it safe to keep using my air conditioner with the U3 error?
In most cases yes, but it's best to address the U3 error soon — see the fix steps below to resolve it.