Mitsubishi Electric MXZ-3C24NA Service Manual page 71

• When thermistor is abnormal.
Check of outdoor thermistors
Disconnect the connector in the following table and
measure the resistance of the thermistor to check
whether the thermistor is normal or not. (Refer to 11-7.)
Normal
Reconnect the connector in the following table and
disconnect the lead wire leading to the compressor.
3 minutes after turning ON the power supply,
start EMERGENCY OPERATION.
Does the unit operate 10 minutes or more without
showing thermistor abnormality?
Yes
Normal
Thermistor
Defrost
Discharge temperature
Outdoor heat exchanger temperature
Ambient temperature
Fin temperature
OBH702A
Abnormal
No
Symbol Connector, Pin No.
RT61 Between CNTH1 pin1 and pin2
Between CNTH1 pin3 and pin4
RT62
RT68 Between CNTH1 pin7 and pin8
Between CNTH2 pin1 and pin2
RT65
RT64 Between CN171 pin1 and pin2
71
Replace the thermistor except RT64.
In case that RT64 is abnormal, replace the
outdoor power P.C. board since RT64 is combined
with the outdoor power P.C. board.
Replace the outdoor control P.C. board or the
outdoor power P.C. board.
Outdoor control P.C. board
Outdoor power P.C. board
Board