Daikin Mini-Split Code U3
Warning
Check operation is not conducted. The multi-zone system was started without the installer running the required commissioning check operation.
Manual wording: “U3 Check operation is not conducted”
Documented for: RMXS multi-split systems
Likely causes, most common first
- Check operation was never executed after installation
When to call a technician
This one is purely an installer step - the check operation is started from a button on the outdoor unit's service PCB. Call whoever installed the system.
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