Mitsubishi Electric SUZ-KA25VA Technical & Service Manual page 77

• When thermistor is abnormal.
v v Check of outdoor thermistors
Disconnect the connector in the outdoor electronic control P.C. board or the outdoor power board
(see below table), and measure the resistance of thermistor. Is the thermistor normal?
No
Reconnect the connector CN661 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
Defrost thermistor
Discharge temperature thermistor
Outdoor heat exchanger temperature thermistor
Fin temperature thermistor
Ambient temperature thermistor
• Fan motor does not operate or stops operating shortly after starting the operation.
w w Check of outdoor fan motor
Start
Check the connection between the
connector CN931 and CN932.
Is the resistance between each terminal
of outdoor fan motor normal?
No
(Fixed to either 5V or 0V DC)
No
Replace the outdoor DC fan motor.
[SUZ-KA50VA
No
Replace the outdoor electronic
control P.C. board.
Symbol
Connector, Pin No.
Between CN661 pin1 and pin2 on the outdoor electronic control P.C. board
RT61
Between CN661 pin3 and pin4 on the outdoor electronic control P.C. board
RT62
Between CN661 pin7 and pin8 on the outdoor electronic control P.C. board
RT68
Between CN3 pin1 and pin2 on the outdoor power board
RT64
Between CN663 pin1 and pin2 on the outdoor electronic control P.C. board
RT65
Yes
Disconnect CN932 from outdoor electronic control P.C. board, and
turn on the power supply.
Rotate the outdoor fan motor manually and measure the voltage of
CN931.
Between 1(+) and 5(-)
Between 2(+) and 5(-)
Between 3(+) and 5(-)
Does the voltage between each terminal become 5V DC and 0V DC
repeatedly?
Does the outdoor fan motor rotates smoothly?
Replace the outdoor electronic control P.C. board.
77
.TH SUZ-KA60VA .TH SUZ-KA71VA
(1) (1)
Yes
Yes
Yes
.TH]
(1)
Replace the thermistor.