Mitsubishi Electric MXZ-SM36NAM2 Technical & Service Manual page 113

Check method of DC fan motor (fan motor/outdoor multi controller circuit board)
1. Notes
• High voltage is applied to the connecter (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
2. Self check
Symptom: The outdoor fan cannot rotate.
Fuse check
Check the fuse (JP50) on outdoor
controller board.
Yes
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))
1
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.
2
3 When 5 minutes have passed since turning ON the breaker, turn SW7-1 ON.
4
Check the voltage of the outdoor multi controller circuit board.
Measure the voltage in the outdoor multi controller circuit
: V
TEST POINT
(between 1 (+) and 4 (-) of the fan connector): V
1
DC
: V
TEST POINT
(between 5 (+) and 4 (-) of the fan connector): V
2
CC
: V
TEST POINT 3
(between 6 (+) and 4 (-) of the fan connector): V
CC
Is the voltage normal?
No
Replace outdoor multi
controller circuit board.
Check the operation.
Fail
Replace defective the 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 ambient temperature.
It is not abnormal; the operation ensures reliability of the product.
OCH810A
board and fan motor.)
Disconnect the FAN motor connector and
measure the resistance of connector pins.
Refer to "8-7. HOW TO CHECK THE PARTS".
Yes
Correct the wiring.
board.
Yes
Replace defective the fan motor.
Check the operation of fan.
Replace outdoor multi controller circuit board.
OK
Complete.
Is the fan motor normal?
Replace outdoor multi controller circuit board
(MULTI.B.) and the defective fan motor.
290–330 V DC(When PAM stops), 380 V DC (When PAM is operating)
DC
15 V DC
CC
0-6.5 V DC
CC
Yes
OK
Complete.
Fail
113
Yes
Replace outdoor multi controller
circuit board (MULTI.B.).
No