HVAC Code Lookup

Mitsubishi Electric Mini-Split Code P8

Soft lockout

Pipe temperature error. The indoor coil never reached the expected cooling or heating temperature range within the allowed time after the compressor started, which means the coil is not actually cooling or heating the way it should.

Manual wording: “Pipe temperature - Detected as abnormal when the pipe temperature is not in the cooling range 3 minutes after compressor start”

Documented for: A-Control indoor units (PKA-A, PLA-A, PEAD-A and M-Series with a wired controller)

Likely causes, most common first

  1. Only a slight temperature difference between room air and pipe temperature - shortage of refrigerant, thermistor holder fallen off the pipe, or a defective refrigerant circuit
  2. Reverse connection of the extension pipe (on multi-unit installations)
  3. Reverse wiring of the indoor/outdoor connecting wire (on multi-unit installations)
  4. Defective detection by the room and pipe temperature thermistors
  5. Stop valve is not opened completely

What you can safely check yourself

  • Check that the outdoor unit is clear of snow, ice and debris
  • Turn the system off at the breaker, wait one minute, and turn it back on once

When to call a technician

Every cause on the manual's list - refrigerant charge, pipe routing, stop valves, sensor mounting - is a technician job.

A Mitsubishi Electric mini-split throwing this code repeatedly has a reason — clearing the code without fixing the cause just hides it.

Sources

Other Mitsubishi Electric codes