Mitsubishi Heavy Industries FDTCVA SERIES Technical Manual page 258

Only in case of FDKN
CnM
1 and 3 (Red - Black)
DC280V?
YES
CnM
4 and 3 (White-Black)
DC15V?
YES
Does the
fan motor turn
smoothly by
hand?
YES
Is the voltage
at CnM 5 (Yellow) DC 1V
or higher?
NO
Replace the indoor
unit control PCB.
Only in case of FDTC
CnM1
1 and 3 (Red - White)
DC320V?
YES
CnM2 4 (Blue)
- CnM1 3 (White)
DC15V?
YES
Does the
fan motor turn
smoothly by
hand?
YES
Is the voltage
at CnM2 3 (Black) DC 1V
or higher?
NO
Replace the indoor
unit control PCB.
3 (Black) is GND.
NO
Replace the indoor
unit control PCB.
YES
3 (Black) is GND.
Secondary
NO
side of transformer
(brown-brown) 17V
or more.
NO
Replace the transformer.
NO
Replace the fan motor.
(2)
YES
Note (2) CNM 3 (Black) is GND.
3 (White) is GND.
NO
Replace the indoor
unit control PCB.
YES
3 (White) is GND.
Secondary
NO
side of transformer
(brown-brown) 17V
or more.
NO
Replace the transformer.
NO
Replace the fan motor.
(2)
YES
Note (2) CNM1 3 (White) is GND.
Check the operation data
by the remote controller.
Reset the error code and operate the
fan in fan mode with Lo fan speed.
NO
Does the fan
operate?
YES
Is the error
reproduced?
YES
(1)
When the motor is
running, is the voltage between
NO
blue wire on CnM 6 and black wire on
CnM 3 fluctuating between
0 to 15V?
YES
Replace the indoor
unit control PCB.
Display conditions
±
If an indoor unit fan motor's speed is detected to be less than
200 rpm continuously for 30 seconds, the fan motor stops for 2
seconds. After 2 seconds, it starts again, but this occurs 4 times
within a period of 1 hour.
Check the operation data
by the remote controller.
Reset the error code and operate the
fan in fan mode with Mid fan speed.
NO
Does the fan
operate?
YES
Is the error
reproduced?
YES
(1)
When the motor is
running, is the voltage between
NO
brown wire on CnM2 2 and white wire on
CnM1 3 fluctuating between
0 to 15V?
Note (1) CNM1 3 (White) is GND.
YES
Replace the indoor
unit control PCB.
Display conditions
±
If an indoor unit fan motor's speed is detected to be less than
200 rpm continuously for 30 seconds, the fan motor stops for 2
seconds. After 2 seconds, it starts again, but this occurs 4 times
within a period of 1 hour.
257
- -
NO
Check the
circumstances.
Note (1) CnM 3 (Black) is GND.
NO
Check the
circumstances.