HVAC Code Lookup

Mitsubishi Electric Mini-Split Code P5

Soft lockout

Drain overflow protection / drain pump error. The float switch stayed underwater for 1 minute 30 seconds with the drain pump running, so the compressor and indoor fan shut off to stop water overflowing.

Manual wording: “Drain overflow protection operation - Suspensive abnormality, if drain float switch is detected to be underwater for 1 minute and 30 seconds continuously with drain pump on.”

Documented for: A-Control indoor units with a condensate pump (PKA-A, PLA-A, PEAD-A, PCA-A)

Likely causes, most common first

  1. Malfunction of the drain pump
  2. Defective drainage - clogged drain pump or clogged drain pipe
  3. Defective drain float switch, or the float caught on a moving part
  4. Defective indoor controller board

What you can safely check yourself

  • Check the condensate drain line outside for a clog, kink, ice or debris
  • Check the air filters and clean them, since a dirty filter can make condensate ripple onto the float switch
  • Turn the system off at the breaker, wait one minute, and turn it back on once

When to call a technician

Clearing the internal drain pan, drain pump or float switch means opening the indoor unit. Call a technician, and do not run the unit while it is spilling water.

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