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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.
Is the COMP OFF State?
Start
Execute Forced
operation.
Is the voltage 8V-12V DC between
main-PCB GND and pin No. 6 of CN74 ?
Fan works normally.
Is the voltage 5V DC between
CN30 No. 1 and No. 7 in the main- PCB?
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.
Apply power around 5 minutes
after power OFF.
(to prevent compressor overload.)
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
YES
YES
NO
NO
YES
Is the voltage 8V-12V DC between
main-PCB GND and pin No. 5 of CN74 ?
Is the voltage 5V DC between CN30
No. 8 and No. 14 in the main-PCB?
NO
Is the voltage 8- 12V DC between
main-PCB GND section and CN74 pin No. 4?
NO
YES
Does 7-12V DC alternate with lass than
2V DC between main-PCB GND
nd CN74 pin NO.6?
Exchange or troubleshoot
the main PCB.
Measure with the door closed.
- Door Open: 0V DC
- Door Close : 5V DC
NO
YES
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.
Reference
Does 7-12V DC alternate with lass than
2V DC between main-PCB GND
nd CN74 pin NO.5?
YES
Does 7-12V DC alternate with lass than
2V DC between main-PCB GND
and CN74 pin NO.4?
YES
FOR C-FAN
FOR C-FAN FOR R-FAN FOR F-FAN
FOR R-FAN FOR F-FAN
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