Mitsubishi Electric Mini-Split Code U8
Soft lockout
Outdoor fan motor protection stop. The board is not seeing the expected rotational speed from the DC outdoor fan motor - 100 rpm or below for 15 seconds at 68F or warmer outdoor air, or 50 rpm or below (or 1500 rpm or more) continuously for 1 minute.
Manual wording: “Outdoor fan motor - Abnormal if rotational frequency of the fan motor is not detected during DC fan motor operation.”
Documented for: A-Control outdoor units (PUZ, MUZ, MXZ)
Likely causes, most common first
- Failure in the outdoor DC fan motor
- Failure in the outdoor controller board
What you can safely check yourself
- Turn the power off at the breaker first, then look for leaves, ice, a stick or other debris jamming the outdoor fan blade
- Clear snow and ice from around and on top of the outdoor unit
- Turn the system back on at the breaker once
When to call a technician
If nothing is physically jamming the fan and U8 returns, the fan motor or the control board has failed. Never reach into the outdoor unit with power on. 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