Samsung RM255BASB If fan motor doesn’t working normaly, Door S/W, Door Open 0V DC, Condition

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.

Start

FOR C-FAN

Is the voltage 8- 12V DC between

main-PCB GND section and CN74 pin No. 4?

NO

FOR R-FAN

Is the voltage 8V-12V DC between

main-PCB GND and pin No. 5 of CN74 ?

NO

Is the voltage 5V DC between CN30 No. 8 and No. 14 in the main-PCB?

YES

NO

Is the COMP OFF State?

			Execute Forced
FOR F-FAN	YES
			operation.
Is the voltage 8V-12V DC between		YES
main-PCB GND and pin No. 6 of CN74 ?
	NO
			Fan works normally.
Is the voltage 5V DC between		NO
CN30 No. 1 and No. 7 in the main- PCB?
	YES		Troubleshoot the connections

of the door S/W.

FOR C-FAN

Does 7-12V DC alternate with lass than

2V DC between main-PCB GND

and CN74 pin NO.4?

YES

Reference

			Apply power around 5 minutes
	Measure with the door closed.			In the first power application, the
	- Door Open: 0V DC		after power OFF.	freezer / refrigerator / compressor
	- Door Close : 5V DC		(to prevent compressor overload.)	fans work for 5 minutes regardless
				of the condition.
FOR R-FAN		FOR F-FAN

Does 7-12V DC alternate with lass than	Does 7-12V DC alternate with lass than	NO
2V DC between main-PCB GND	2V DC between main-PCB GND
nd CN74 pin NO.5?	nd CN74 pin NO.6?
YES	YES	Exchange or troubleshoot
		the main PCB.

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.

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.)

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