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Mitsubishi · Heat pump

P4 Drain float switch disconnected

Medium severity Mr. Slim PEAD-RP JA(L) ducted indoor unit

What the control is telling you

Pins 3 and 4 of the float switch connector CN4F are not closed, so the board thinks the float switch is unplugged. Checked all the time the unit runs. Some controllers show this as 5701.

Applies to: PEAD-RP35/50/60/71/100/125/140JA and JA(L) ducted indoor units (220-240 V models)

Likely causes

  • Float switch connector CN4F loose or not plugged in
  • Faulty indoor control board

Test and repair steps

  1. Turn the unit off at the remote first, then switch off the breaker before opening the unit or unplugging connectors.
  2. Check that the float switch plug is fully seated in CN4F and reseat it.
  3. Power up and see if the code clears.
  4. Test run briefly with pins 3-4 of CN4F jumpered. If P4 still shows, replace the indoor control board.
  5. Do not leave the jumper in place - it disables overflow protection.

Models that show this code

14 models in Mr. Slim PEAD-RP JA(L) ducted indoor unit

PEAD-RP100JAPEAD-RP100JALPEAD-RP125JAPEAD-RP125JALPEAD-RP140JAPEAD-RP140JALPEAD-RP35JAPEAD-RP35JALPEAD-RP50JAPEAD-RP50JALPEAD-RP60JAPEAD-RP60JALPEAD-RP71JAPEAD-RP71JAL

Other codes on the same units

  • E6 Indoor/outdoor communication - indoor not receiving
  • E7 Indoor unit transmit error to outdoor unit
  • P1 Room (intake) air sensor TH1 open or shorted
  • P2 Liquid pipe sensor TH2 open or shorted
  • P5 Drain overflow - float switch wet with pump running
  • P6 Coil freeze or overheat protection
  • P8 Pipe temperature out of range (coil not cooling or heating)
  • P9 Coil sensor TH5 open or shorted

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Source: Mitsubishi Electric PEAD-RP35-140JA(L) Service Manual, 10-3 Self-diagnosis action table, p.31. Summarized in our own words; check the original manual for your model.

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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.