Daikin Mini-Split Code A3
Soft lockout
Drain level control system abnormality. The condensate float switch detected water at its upper limit and turned off, so the unit stops to avoid overflowing.
Manual wording: “A3 Drain level control system abnormality”
Documented for: Ducted, cassette and other indoor units with a condensate pump (FDXS/CDXS/FFQ on RMXS multi-split systems)
Likely causes, most common first
- Defective drain pump
- Improper drain piping work
- Clogged drain piping
- Defective float switch
- Defective indoor unit PCB
- Defective short circuit connector X15A on indoor unit PCB
What you can safely check yourself
- Check the condensate drain line outlet outside for a clog, kink or blockage
- Check for water pooling under the indoor unit and shut the system off if it is overflowing
- Turn the system off at the breaker or disconnect switch and back on once after the drain is clear
When to call a technician
If the drain line is clear and A3 comes back, the drain pump or float switch is failing and needs a technician - a plugged drain that keeps refilling will damage the unit and the wall.
A Daikin mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- 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