Mitsubishi Electric MXZ-A18WV Service Manual page 65

• Fan motor does not operate or stops operating shortly after starting the operation.
G G Check of outdoor fan motor
MXZ-A18WV
Start
Check the connection of connector CN851 in the fan motor relay connector and outdoor electronic control P. C. board
at the noise filter P. C. board and connector CN901 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. 3 minutes after turning on the power supply,
start EMERGENCY OPERATION.
2. Check the voltage between pin 3 and pin 4, pin 3 and pin 5 at the fan motor connector.
Is there voltage of 230V AC?
No
1. Turn off power supply of the indoor and outdoor unit, and disconnect the connector
(CN851).
2. Is the voltage 0V, when the voltage between CN851 pin3 (+), pin7 (-), pin6 (-) are
measured after the power supply is turned on the outdoor unit?
Yes
3 minutes after turning on the power supply, start EMERGENCY OPERATION.
Is there voltage of 12V DC between CN851 pin3 (+) and pin6 (-)?
Yes
Replace the noise filter P. C. board.
MXZ-A26/A32WV
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.
Yes
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.
65
Abnormal
No
No
Yes
Yes
Replace the fan motor.
Replace the oudtoor
electronic control P. C.
board.