Mitsubishi Electric Mini-Split Code EC
Soft lockout
Startup time over. The system could not finish its startup process within 4 minutes of power-on.
Manual wording: “Startup time over - The unit cannot finish startup process within 4 minutes after power on.”
Documented for: A-Control outdoor units (PUZ, MUZ, MXZ)
Likely causes, most common first
- Contact failure of the indoor/outdoor unit connecting wire
- Connecting wire diameter or length is outside the specified capacity
- Two or more outdoor units set to refrigerant address 0 in a group control system
- Noise on the power supply or connecting wire
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
Connecting-wire condition and length are installation items only a technician should verify.
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