Mitsubishi Electric Mini-Split Code U6
Soft lockout
Power module abnormality / compressor overcurrent interruption. The board checked the power module after detecting overcurrent (a UF or UP condition) and found it abnormal.
Manual wording: “Power module - Check abnormality by driving power module in case overcurrent is detected. (UF or UP error condition)”
Documented for: A-Control outdoor units (PUZ, MUZ, MXZ)
Likely causes, most common first
- Outdoor stop valve is closed
- Decrease of power supply voltage
- Looseness, disconnection or reversed connection of the compressor wiring
- Defective compressor
- Defective outdoor power circuit board
What you can safely check yourself
- Check that the breaker feeding the outdoor unit is on and has not tripped
- Turn the system off at the breaker, wait one minute, and turn it back on once
When to call a technician
Stop valves, compressor wiring and the inverter power module are all high-voltage refrigerant-circuit items. Call a technician.
A Mitsubishi Electric mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.
Source
- Service Manual No. OCH750 Revised Edition-E - PUZ-HA Outdoor Units (May 2024) (Mitsubishi Electric, PUZ-HA24NHA1, PUZ-HA30NKA, PUZ-HA36NKA, PUZ-HA42NKA1 heat-pump outdoor units) · checked 2026-08-25