Mitsubishi Electric Mini-Split Code F3
Soft lockout
The 63L low pressure switch connector (red) on the outdoor controller board is open. Detected when power is turned on.
Manual wording: “F3 63L connector(red) is open.”
Documented for: PUZ-HA and other A-Control outdoor units fitted with a low pressure switch
Likely causes, most common first
- 63L connector disconnected or has contact failure on the outdoor controller board
- 63L low pressure switch itself has failed or is tripped
- Defective outdoor controller circuit board
What you can safely check yourself
- Turn the system off at the breaker, wait one minute, and turn it back on once
When to call a technician
63L is a refrigerant pressure safety switch. Never jumper or bypass it - a technician must find out why it is open.
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