LG Mini-Split Code CH39
Soft lockoutShown as: Outdoor LED01 (red) blinks 3 times, LED02 (green) blinks 9 times
Communication error between the PFC MICOM and the inverter MICOM - the two microcontrollers on the outdoor unit's power board have lost contact with each other.
Manual wording: “Communication Error between PFC MICOM and Inverter MICOM”
Documented for: LG Multi F / Multi F MAX outdoor units
What you can safely check yourself
- Turn the system off at the breaker for three minutes and back on
When to call a technician
This is an internal fault between processors on the outdoor inverter board. A technician has to diagnose and usually replace the board.
A LG mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- MULTI F / MULTI F MAX Outdoor Unit Installation Manual (LG Electronics U.S.A., Inc., Multi F and Multi F MAX multi-zone heat pump outdoor units (LMU series) with standard wall-mount, Art Cool, cassette and ducted indoor units) · checked 2026-08-25