When Thermistor Is Abnormal.; Fan Motor Does Not Operate Or Stops Operating Shortly After Starting The Operation - Mitsubishi Electric MSC-A07WV Service Manual

• When thermistor is abnormal. (When the LED display is a table below.)
O O Check of outdoor unit thermistor
Start
Disconnect the connector in the outdoor electronic control P. C. board (see below table),
and measure the resistance of thermistor to check whether the thermistor is normal or not.
Normal
Reconnect the connector (CN661, CN662 and CN663) and disconnect the lead wire leading to the compressor.
3 minutes after turning on the power supply, start EMERGENCY OPERATION.
Does thermistor operate 10 minutes or more though the
thermistor abnormality is not displayed?
Yes
Normal
Thermistor
Discharge temperature thermistor
Defrost thermistor
Evaporation temperature thermistor
High-pressure protect thermistor
Gas pipe temperature A thermistor
Gas pipe temperature B thermistor
Fin temperature thermistor

• Fan motor does not operate or stops operating shortly after starting the operation.

P P Check of outdoor fan motor
Start
Check the connection of connector (CN851) in the fan motor relay connector and outdoor electronic control P. C. board
at the noise filter P. C. board and connector (CN901) in the noise filter board.
Disconnect the fan motor connector, and measure the resistance of the
fan motor winding to check the winding characteristic.
Normal
1. Disconnect the lead wire leading to the compressor. Turn on power supply to the
indoor and outdoor unit. Three minutes later, start EMERGENCY OPERATION.
2. Check the voltage between pin 3 and pin 4, pin 3 and pin 5 at the fan motor connector.
Is there voltage of 230V AC?
No
1. Turn off power supply of the indoor and outdoor unit, and disconnect the connector
(CN851).
2. Is the voltage 0V, when the voltage between CN851 pin3 (+), pin7 (-), pin6 (-) are
measured after the power supply is turned on the outdoor unit?
Yes
Is there voltage of 12V DC between CN851 pin3 (+) and pin6 (-), when power supply
turns on the indoor unit and EMERGENCY OPERATION starts in three minutes.
Yes
Replace the noise filter P. C. board
<MXZ-A18WV>
No
Symbol
RT61 Between CN662 pin3 and pin4
RT62 Between CN662 pin1 and pin2
RT63 Between CN662 pin5 and pin6
RT68 Between CN662 pin7 and pin8
RT6A Between CN661 pin1 and pin2
RT6B Between CN661 pin3 and pin4
RT65 Between CN663 pin1 and pin2
<MXZ-A18WV>
Yes
122
Abnormal
Replace the outdoor electronic
control P. C. board.
Connector, Pin No.
Abnormal
No
No
Replace the thermistor
Replace the fan motor
Replace the oudtoor
electronic control P. C.
board