Samsung RM255BABB Training Manual page 68

DIAGNOSTIC
6-7) If fan motor doesn't working normaly.
This refrigerator uses a BLDC FAN motor and this motor is driven by 8 ~12V DC.
Under the normal condition of COMP ON, it is operated together with F-FAN motor. F-Fan motor may not work
depending on the conditions. If the door is opened and closed once at a high ambient temperature, the BLDC motor
would be operated after 1 minute or delayed longer. Therefore, you are advised not to take it for an error.
FOR C-FAN
Is the vol t age 8- 12V DC between
mai n -PCB GND secti o n and CN74 pi n No. 4?
NO
FOR C-FAN
Does 7-12V DC al t ernate wi t h l a ss than
2V DC between mai n -PCB GND
and CN74 pi n NO.4?
YES
Reference
CN74 pin #3(F-FAN), pin #2(R-FAN), and pin #1(C-FAN) will get pulse signals generated as motor rotates. These signals will
be input into MICOM. If signals are not input into the motor operation, it will re-operate 10 seconds after the fan OFF. But if
signals are not still input, the above operation will be performed four more times. If signals keep failing to be input, the motor
will be started again after 10 minutes. This function is effective to secure the normal operation where the motor would be
restrained due to foreign matters such as ice.
FOR R-FAN
Is the vol t age 8V-12V DC between
mai n -PCB GND and pi n No. 5 of CN74 ?
NO
Is the voltage 5V DC between CN30
No. 8 and No. 14 in the main-PCB?
YES
Measure with the door closed.
- Door Open: 0V DC
- Door Close : 5V DC
FOR R-FAN
Does 7-12V DC al t ernate wi t h l a ss than
2V DC between mai n -PCB GND
nd CN74 pi n NO.5?
YES
67 67
Start
Is the COMP OFF State?
FOR F-FAN
YES
Is the voltage 8V-12V DC between
main-PCB GND and pin No. 6 of CN74 ?
NO
Is the voltage 5V DC between
CN30 No. 1 and No. 7 in the main- PCB?
YES
Apply power around 5 minutes
after power OFF.
(to prevent compressor overload.)
FOR F-FAN
NO
Does 7-12V DC al t ernate wi t h l a ss than
2V DC between mai n -PCB GND
nd CN74 pi n NO.6?
YES
Expected causes :
1. Fan motor itself has a failure.
2. Wire connections have a contact problem.
3. Check : Input of the fan motor rotation pulse for fan motor operation.
(See the details in Fan Motor Drive Circuit section.)
NO
Execute Forced
operation.
YES
Fan works normally.
NO
Troubleshoot the connections
of the door S/W.
In the first power application, the
freezer / refrigerator / compressor
fans work for 5 minutes regardless
of the condition.
Exchange or troubleshoot
the main PCB.