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