Troubleshooting - Mitsubishi Electric SLH Series Technical & Service Manual

Split-type, heat pump air conditioners, ceiling cassettes, indoor unit
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9

TROUBLESHOOTING

1. Cautions on troubleshooting
(1) Before troubleshooting, check the followings:
1Check the power supply voltage.
2Check the indoor/outdoor connecting wire for mis-wiring.
(2) Take care the followings during servicing.
1 Before servicing the air conditioner, be sure to first turn off the remote controller to stop the main unit, and then turn
off the breaker.
2 When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the
components.
3 When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.
2. Trouble display
Blinking frequency of operation lamp shows the details of trouble in case trouble happens while indoor and
outdoor units.
(1) Incase of being indicated irregularity on the self diagnoses.
Blinking
Phenomenon
frequency
1
Mis-wiring
blinking
Indoor-outdoor
signal error
2
Indoor coil thermistor
blinking
Room temperature
thermistor
Drain sensor
Operation lamp
Cause
Wiring between the indoor and
outdoor is coming off.
Difference of wiring polarity
between the indoor and outdoor.
Trouble of the outdoor deicer
P.C. board.
Trouble of the Indoor controller
board.
Mis-connecting of the Indoor coil
thermistor.
Trouble of the Indoor coil
thermistor.
Trouble of the Indoor controller
board.
Mis-connecting of the room
temperature thermistor.
Trouble of the room temperature
thermistor.
Trouble of the Indoor controller
board.
Mis-connecting of the indoor drain
sensor
Trouble of the indoor drain sensor
Trouble of the Indoor controller
board.
56
Countermeasure
Check the wiring out between the indoor and
outdoor.
Check the deicer P.C.board out.
Exchange the Indoor controller board.
Reinsert the connector (CN21).
Check the resistance value of the thermistor.
Exchange the Indoor controller board.
Reinsert the connector (CN20).
Check the resistance value of the thermistor.
Exchange the Indoor controller board.
Reinsert the connector (CN31).
Check the resistance value of the thermistor.
Exchange the Indoor controller board.
To be continued on the next page.

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