HVAC Code Lookup

Mitsubishi Electric Mini-Split Code EA

Soft lockout

Miswiring of the indoor/outdoor unit connecting wire, or too many indoor units. The outdoor board could not automatically count the connected indoor units within 4 minutes of power-on, or it counted more indoor units than the outdoor unit supports.

Manual wording: “Miswiring of indoor/outdoor unit connecting wire - Outdoor controller circuit board can automatically check the number of connected indoor units. Abnormal if the number cannot be checked automatically due to miswiring.”

Documented for: A-Control outdoor units (PUZ, MUZ, MXZ)

Likely causes, most common first

  1. Contact failure or miswiring of the indoor/outdoor unit connecting wire
  2. Connecting wire diameter or length is outside the specified capacity (total wiring length limit 80 m)
  3. Too many indoor units connected to one outdoor unit (4 units or more)
  4. Defective transmitting/receiving circuit on the outdoor or indoor controller board
  5. Two or more outdoor units set to refrigerant address 0
  6. 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

This is almost always an installation wiring fault. The connecting wire order S1, S2, S3 and the unit count have to be checked by 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

Other Mitsubishi Electric codes