Mitsubishi Electric MXZ-A14WV Service Manual page 64

• When thermistor is abnormal. (When the LED display is a table below.)
F F Check of outdoor unit thermistors
MXZ-A14/A18WV
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 on the outdoor electronic control P.C. board, and disconn-
ect 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
MXZ-A26/A32WV
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 and CN662 on the outdoor electronic control P.C. board and CN3 on the power
board, 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
Outdoor heat exchanger 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
No
Replace the outdoor electronic
control P.C. board.
Symbol Connector, Pin No.
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
No
Replace the outdoor electronic
control P.C. board.
Symbol Connector, Pin No.
RT61 Between CN661 pin3 and pin4
RT62 Between CN661 pin1 and pin2
RT63 Between CN661 pin5 and pin6
RT68 Between CN661 pin7 and pin8
RT6A Between CN662 pin1 and pin2
RT6B Between CN662 pin3 and pin4
RT6C Between CN662 pin5 and pin6
RT6D Between CN662 pin7 and pin8
RT65 Between CN3 pin1 and pin2
64
Abnormal
Replace the thermistor.
Abnormal
Replace the thermistor.