Mitsubishi Electric MXZ-32SV Service Manual page 32

• When thermistor is abnormal. (When the LED display is a table below.)
F F 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.
Turn on power supply to the indoor and outdoor unit. Three minutes later EMERGENCY OPERATION starts.
Does thermistor operate 10 minutes or more though the
thermistor abnormality is not displayed?
Yes
Normal
Thermistor
Defrost thermistor
Discharge temperature thermistor
Evaporation temperature thermistor
Gas pipe temperature thermistor (Unit A)
Gas pipe temperature thermistor (Unit B)
Gas pipe temperature thermistor (Unit C)
Gas pipe temperature thermistor (Unit D)
Fin temperature thermistor
• Fan motor does not operate. Or, fan motor stops at once' after fan motor operates.
G G 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, EMERGENCY OPERATION starts.
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 220V AC - 240V 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 pin3 (-), when power supply
turns on the indoor unit and EMERGENCY OPERATION starts in three minutes.
Yes
Replace the noise filter P. C. board
No
Replace the electronic
control P. C. board.
Symbol
RT62 Between CN661 pin1 and pin2
RT61 Between CN661 pin3 and pin4
RT63 Between CN661 pin5 and pin6
RT66 Between CN662 pin1 and pin2
RT67 Between CN662 pin3 and pin4
RT68 Between CN662 pin5 and pin6
RT69 Between CN662 pin7 and pin8
RT65 Between CN663 pin1 and pin2
Yes
32
Abnormal
Connector, Pin No.
Abnormal
No
No
Replace the thermistor
Replace the fan motor
Replace the electronic
control P. C. board