Check Of Thermistor; Check Of Fan Motor - Mitsubishi Electric MSH09TW Service Manual

•When thermistor is abnormal. (When the LED displayis a table below)
N N Check of thermistor
Start
Disconnect the connector in the 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 suppy, 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
Fin temperature thermistor
Gas pipe temperature thermistor (Unit A)
Gas pipe temperature thermistor (Unit B)
Gas pipe temperature thermistor (Unit C)
•Fan motor does not operate or stops operating shortly after starting the operation.
O O Check of fan motor
Start
Check the connection of connector (CN851, CN852) in the fan motor relay connector and electronic control P. C. board
at the noise filter P. C. board and connector (CN901, CN902) 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 2 and pin 3, pin 2 and pin 5, pin 2 and pin 6 at the fan motor connector.
Is there voltage of 208V AC - 230V AC?
No
1. Turn off power supply of the indoor and outdoor unit, and disconnect the connector
(CN851, CN852).
2. Is the voltage 0V, when the voltage between CN852 pin1 (+) and CN851 pin1 (-),
pin2 (-), or pin3 (-) are measured after the power supply is turned on the outdoor unit?
Yes
Is there voltage of 12V DC between CN852 pin1 (+) and CN851 pin3 (-), when power
supply turns on the indoor unit and EMERGENCY OPERATION starts in three minutes.
Yes
Replace the noise filter P. C. board
(MXZ30TN MXZ30TN2)
Symbol
RT61
RT62
RT63
RT65
RT66
RT67
RT68
(MXZ30TN MXZ30TN2)
Yes
No
Replace the electronic
control P. C. board.
Connector, Pin No.
Between CN661 pin3 and pin4
Between CN661 pin1 and pin2
Between CN661 pin5 and pin6
Between CN663 pin1 and pin2
Between CN662 pin1 and pin2
Between CN662 pin3 and pin4
Between CN662 pin5 and pin6
92
Abnormal
Replace the thermistor
Abnormal
Replace the fan motor
No Replace the electronic
control P. C. board
No