HVAC Code Lookup

Mitsubishi Electric Mini-Split Code P6

Warning

Freezing or overheating protection is working. In cooling the indoor coil dropped below 5F for 3 minutes twice inside 16 minutes; in heating the coil went above 158F twice inside 30 minutes. Either way the unit stops itself to protect the coil.

Manual wording: “Freezing/overheating protection is working ... 1 Clogged filter (reduced airflow) 2 Short cycle of air path”

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. Clogged filter reducing airflow
  2. Short cycle of the air path - supply air blowing straight back into the return
  3. Low-load (cooling) or overload (heating) operation outside the tolerance range
  4. Defective indoor fan motor
  5. Defective outdoor fan control
  6. Overcharge of refrigerant
  7. Defective (clogged) refrigerant circuit

What you can safely check yourself

  • Remove and clean or replace the air filters - the manual's first listed check is 'Check clogs of the filter'
  • Remove anything blocking the indoor unit air inlet or outlet, including furniture, curtains and boxes
  • Check that the outdoor unit is clear of snow, ice, leaves and debris
  • Turn the system off at the breaker, wait one minute, and turn it back on once

When to call a technician

If the filters are clean and airflow is unobstructed and P6 comes back, the fan motor or the refrigerant charge is the problem and a technician has to diagnose it.

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