Daikin Mini-Split Code UH
Soft lockout
System abnormality, refrigerant system address undefined. The outdoor unit found an indoor unit that never got an auto-assigned address.
Manual wording: “UH System abnormality, refrigerant system address undefined”
Documented for: RMXS and other multi-zone systems
Likely causes, most common first
- Improper connection of transmission wiring between indoor and outdoor unit
- Defective indoor unit PCB
- Defective main PCB (A1P)
What you can safely check yourself
- If the system was just powered up for the first time, allow at least 12 minutes for auto-addressing before reading the code again
When to call a technician
If UH is still there after auto-addressing has had time to finish, a technician has to trace the transmission wiring between the indoor units and the outdoor unit.
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