Trane Mitsubishi Electric CITY MULTI Series Technical & Service Manual page 34

9-1-3. DC Fan motor (fan motor/indoor controller board)
Check method of indoor fan motor (fan motor/indoor controller board)
Notes
1
· High voltage is applied to the connector (CNMF) for the fan motor. Pay attention to the service.
· Do not pull out the connector (CNMF) for the motor with the power supply on.
(It causes trouble of the indoor controller board and fan motor.)
Self check
2
Conditions: The indoor fan cannot rotate.
Wiring contact check
Contact of fan motor connector (CNMF)
Contact of power supply cable
Is there contact failure ?
No
Power supply check (Remove the connector (CNMF))
Measure the voltage in the indoor controller circuit
TEST POINT
1: V (between 1 (+) and 4 (−) of the fan connector): V
DC
TEST POINT
2: V (between 5 (+) and 4 (−) of the fan connector): V
CC
Is the voltage normal?
Yes
Fan motor position sensor signal check
Turn around the fan motor more than one revolution slowly, and check
the voltage TEST POINT4 V
Does the voltage repeat 0 and 15 VDC?
Yes
Replace the indoor controller board.
Check the operation of fan.
Fail
Replace the defective fan motor.
OCHT746A
Yes
Correct the wiring.
board.
No
Trouble of the indoor controller board.
Replace the indoor controller board.
(between 7(+) and 4(−)).
FG
No
OK
Complete.
294–325 VDC
DC
15 VDC
CC
Check the operation of fan.
Replace the defective fan motor.
Trouble of the fan motor.
Replace the defective fan motor.
Yes
Check the operation of fan.
Fail
Replace the indoor
controller board.
34
Yes
OK
Complete.
Fail
OK
Complete.