ErrorCodeDoctor
Daikin Air Conditioner AJ error code
The AJ error means your Daikin air conditioner detected a capacity setting fault. This typically occurs after an indoor unit PCB has been replaced without installing the capacity setting adaptor, or the PCB itself is defective. Contact a qualified technician to install the correct capacity setting adaptor.
Common causes
- Capacity setting adaptor was not installed after replacing the PCB
- Defective indoor unit PCB
How to fix it
-
1
Contact a qualified technician to install the correct capacity setting adaptor or inspect the PCB
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
AJ error — frequently asked questions
What does the AJ error mean on a Daikin air conditioner?
A capacity setting fault was detected in the indoor unit PCB
What causes the AJ error?
The AJ error is usually caused by: Capacity setting adaptor was not installed after replacing the PCB; Defective indoor unit PCB.
Can I fix the AJ 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 AJ error?
Fixing the AJ 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 AJ error?
We'd recommend addressing the AJ error before continuing to use the air conditioner, since hard-rated issues often involve a real fault rather than a minor glitch.