Mitsubishi Electric MXZ-SM72TAM-U1 Service Manual page 95

8-7-2. Check method of DC fan motor (fan motor/outdoor multi controller circuit
board)
■ Precaution
• High voltage is applied to the connector (CNF1, 2) for the fan motor. Pay attention to the service.
• Do not pull out the connector (CNF1, 2) for the motor with the power supply on. (It causes trouble of the outdoor multi
controller circuit board and fan motor.)
■ Self-check
Symptom: The outdoor fan cannot rotate.
Fuse check
Check the fuse (JP50) on outdoor
multi controller circuit board.
Did the fuse blow?
No
Wiring contact check
Contact of fan motor connector
(CNF1, 2)
Is there contact failure?
No
Power supply check (Remove the connector (CNF1, 2))
While the breaker is OFF, disconnect the compressor wirings (U/V/W) from the outdoor power circuit board.
While the breaker is OFF, disconnect the fan motor connector CNF1, 2.
When 5 minutes have passed since turning ON the breaker, turn SW7-1 ON.
Check the voltage of the outdoor multi controller circuit board.
Measure the voltage in the outdoor controller circuit board.
TEST POINT 1: V
: V
TEST POINT 2: V
TEST POINT 3: V
Is the voltage normal?
No
Replace the outdoor multi
controller circuit board.
Check the operation.
Fail
Replace the defective fan
motor.
Note:
• Turn SW7-1 OFF after the troubleshooting completes.
• The fan sometimes starts on-off cycle operation during low load operation or cooling at low outside temperature.
It is not abnormal; the operation ensures reliability of the product.
OCH800A_95
Disconnect the FAN motor
connector and measure the
Yes
resistance of connector
pins.
Refer to "How to check the
parts".
Yes
Correct the wiring.
(between 1 (+) and 4 (−) of the fan connector): 290–330 V DC (3-phase)
DC
(between 1 (+) and 4 (−) of the fan connector): 290–330 V DC (when PAM stops),
DC
(between 5 (+) and 4 (−) of the fan connector): V
CC
(between 6 (+) and 4 (−) of the fan connector): V
CC
Yes
Replace the faulty fan motor.
Replace the outdoor multi
controller circuit board.
OK
Complete.
Is the fan motor normal?
Replace the outdoor multi controller circuit
board (MULTI.B.) and the faulty fan motor.
380 V DC (when PAM is operating) (1-phase)
15 V DC
CC
0–6.5 V DC
CC
Yes
Check the operation of fan.
Fail
Yes
Replace the outdoor multi
controller circuit board (MULTI.B.).
No
OK
Complete.