Mitsubishi Electric PEFV-P72NMHSU-E Technical & Service Manual page 23

1. Error Code
0403
Serial communication error (Indoor unit)
2. Error definition and error detection method
Serial communication cannot be established between the Indoor controller board and the INV board.
3. Cause, check method and remedy
(1) Faulty wiring
Check the following wiring connections.
1) Between Indoor controller board and Power supply board
Indoor controller board Power supply board
CN100
2) Between Power supply board and INV board
Power supply board INV board
CNRSP CNRS2
(2) INV board failure or Indoor controller board failure or Power supply board failure
If the error persists after a power reset, replace the INV board, the Indoor controller board, or the Power supply board.
Refer to section [8] Troubleshooting, item 3. DC fan motor (fan motor/INV board) for error codes related to the inverter.
(page 47)
1. Error Code
2500
Drain sensor submergence (Models with a drain sensor)
2. Error definition and error detection method
1) If an immersion of the drain sensor in the water is detected while the unit is in any mode other than the Cool/Dry mode and
when the drain pump goes from OFF to ON, this condition is considered preliminary water leakage. While this error is being
detected, humidifier output cannot be turned on.(Applicable to the units manufactured in or after October 2006)
2) If the immersion of the sensor in the water is detected four consecutive times at an hour interval, this is considered water leak-
age, and "2500" appears on the monitor.
3) Detection of water leakage is also performed while the unit is stopped.
4) Preliminary water leakage is cancelled when the following conditions are met:
One hour after the preliminary water leakage was detected, it is not detected that the drain pump goes from OFF to ON.
The operation mode is changed to Cool/Dry.
The liquid pipe temperature minus the inlet temperature is -10°C [-18°F] or less.
3. Cause, check method and remedy
(1) Drain water drainage problem
Clogged drain pump
Clogged drain piping
Backflow of drain water from other units
(2) Adhesion of water drops to the drain sensor
Trickling of water along the lead wire
Rippling of drain water caused by filter clogging
(3) Failure of the relay circuit for the solenoid valve
(4) Indoor controller board failure
Drain sensor circuit failure
HWE1017B
CNRSC
Cause Check method and remedy
Check for proper drainage.
1) Check for proper lead wire installation.
2) Check for clogged filter.
Replace the relay.
If the above item checks out OK, replace the indoor control-
ler board.
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