Mitsubishi MUZ-A18YV Service Manual page 39

• When OPERATION INDICATOR lamp flashes 6-time.
• When thermistor is abnormal. (When the LED display is a table below.)
F F Check of outdoor thermistors
Start
Disconnect the connector in the electronic control P.C. 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
Discharge temperature thermistor
Defrost thermistor
Outdoor heat exchanger temperature thermistor
Fin temperature thermistor
• Fan motor does not operate or stops operating shortly after starting the operation.
G G 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.
No
Replace the outdoor electronic
control P.C. board.
Symbol
Connector, Pin No.
Between CN661 pin3 and pin4
RT61
Between CN661 pin1 and pin2
RT62
Between CN661 pin7 and pin8
RT68
Between CN3 pin1 and pin2
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.
39
Yes
Yes
Yes
Replace the thermistor.