Daikin Mini-Split Code A1
Hard lockout
Indoor unit PCB abnormality. The indoor unit's microcomputer checked itself and either the internal circuit is not working or it cannot load its internal settings.
Manual wording: “Indoor A1 Indoor unit PCB abnormality”
Documented for: FTXS-L, FDXS-L, H-Series, FTXM-W/V (Atmosphera), RMXS multi-split indoor units
Likely causes, most common first
- Wrong models interconnected (indoor and outdoor unit are not a matched pair)
- Defective indoor unit PCB
- Disconnection of a connector on the indoor PCB
- Reduction of power supply voltage
What you can safely check yourself
- Turn the system off at the breaker or disconnect switch, wait a minute, and turn it back on once
- Check the breaker for the indoor and outdoor unit is fully on
When to call a technician
A1 is an indoor control board fault. Checking connectors, supply voltage and model compatibility means opening the indoor unit electrical box, which is a technician's job.
A Daikin mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Sources
- Service Manual - Inverter Pair FTXS-L Series / FDXS-L Series (SiUS091133) (Daikin, FTXS09/12/15/18/24/30/36LVJU wall mount, FDXS09/12LVJU ducted, RKS/RXS09-36LVJU outdoor) · checked 2026-08-25
- Service Manual - Inverter Pair Wall Mounted Type H-Series (SiUS04-924_A) (Daikin, FTXS30/36HVJU indoor, RKS30/36HVJU and RXS30/36HVJU outdoor) · checked 2026-08-25
- Service Manual - Inverter Pair Wall Mounted Type FTXM-W/V Series (SiUS042113EA) (Daikin, FTXM-W / FTXM-V (Daikin Atmosphera) wall-mount heat pump) · checked 2026-08-25
- Service Manual - Multi-Split Type Air Conditioners RMXS-L Series (SiUS181631EA) (Daikin, RMXS48LVJU outdoor, BPMKS048A2U/049A3U branch provider, CTXG/CTXS/FTXS/CDXS/FDXS/FVXS/FFQ indoor units) · checked 2026-08-25