Fujitsu Mini-Split Code 39
Soft lockoutShown as: OPERATION lamp blinks 3 times, TIMER lamp blinks 9 times, ECONOMY lamp blinking continuously
Indoor fan motor power supply error. The indoor board has lost the supply feeding the fan motor, usually from a voltage drop, electrical noise, or an open connector.
Manual wording: “Check external cause at indoor and outdoor units (voltage drop or noise) ... Check if cable is open. (Upon correcting removed connector, reset the power)”
Documented for: AUU18-48RGLX, ARU12-48RGLX
Likely causes, most common first
- Voltage drop or electrical noise from a large load sharing the same circuit
- Defective contact or leakage current in the power supply circuit
- Connector removed, mis-connected, or an open cable to the fan motor
What you can safely check yourself
- Check whether a large appliance shares the same circuit and started at the same time the fault appeared
- Turn the power off at the breaker for about 5 minutes and back on
When to call a technician
Connector and supply-circuit checks are inside the powered electrical box. Leave that to a technician.
A Fujitsu mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- 410A Mini-Split Troubleshooting Guide (Part # 6-26-FG2020 Rev. 5/2019) (Fujitsu General America, Inc., All R410A Halcyon mini-splits: RGLX, RL2/RLS3/RLS3H/RLS3Y/RLB/RLXB/RLXEH wall mounted, RLF/RLF1 multi-zone indoor units, RLXFZ multi-zone outdoor units, RML/RMLQ, RULX/RSLX universal-mount, RCLX cassettes) · checked 2026-08-25