ErrorCodeDoctor
Daikin Air Conditioner A0 error code
The A0 error means an external protection device connected to the indoor unit terminal strip (T1-T2) has been activated. This is a safety shutdown triggered by a device wired into the indoor unit — such as a float switch or external sensor. Contact a qualified technician to inspect the protection device and its wiring.
Common causes
- External protection device wired to the T1-T2 terminals has triggered
- Protection device wiring is defective or has a fault
How to fix it
-
1
Contact a qualified technician to inspect the external protection device and associated wiring
Related Daikin Air Conditioner error codes
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
A6
The indoor unit fan motor has a fault
A0 error — frequently asked questions
What does the A0 error mean on a Daikin air conditioner?
An external protection device connected to the indoor unit has been activated
What causes the A0 error?
The A0 error is usually caused by: External protection device wired to the T1-T2 terminals has triggered; Protection device wiring is defective or has a fault.
Can I fix the A0 error myself?
This is rated a hard fix — it often requires tools, parts, or experience, and may be safer left to a professional technician.
How much does it cost to fix the A0 error?
Fixing the A0 error on a Daikin air conditioner typically costs $80–$250, depending on parts and whether you do it yourself or hire a technician.
Is it safe to keep using my air conditioner with the A0 error?
We'd recommend addressing the A0 error before continuing to use the air conditioner, since hard-rated issues often involve a real fault rather than a minor glitch.