HVACopediaMitsubishi · Mini-split · Pump/purge
Drain overflow protection (P5)
What happens, in order
- Drain float switch is read while the drain pump runs
- If the float switch stays underwater for 1 minute 30 seconds with the pump on, the unit counts a suspected fault
- Compressor and indoor fan are turned off
- If the same condition shows during the suspected fault, a drain pump error is declared
- Check the pump, drain piping and float switch (CN4F); replace the board if CN4F shorts between pins 3-4 and the fault returns
- Cycle power off and on after the check
Timings and thresholds
| Item | Value |
|---|---|
| Float underwater time | 1 min 30 s |
Codes you may see during this
P5 P4
Applies to: Mitsubishi PEAD-RP35JA(L) indoor unit
Models
More Mitsubishi mini-split sequences
- Auto restart after power failure · Startup
- Test run with wireless remote · Startup
- Freezing and overheating protection (P6) · Freeze protection
Take it to the job
Sequences of operation, error codes and tips work offline in the HVACopedia app.
Source: Mitsubishi PEAD-RP35JA(L) service manual, Self-diagnosis action table P5. Written in our own words; timings can differ by model and software version, so check the manual for your exact unit.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.