Samsung RB31FEJNB Series Service Manual page 66

4. TROUBLESHOOTING
4-2-3) When the refrigerator(R) FAN does not work (restricted to R-FAN applied models only)
- This refrigerator uses BLDC FAN motor.
BLDC motor operates by DC 7~12V.
- Generally, under COMP ON condition, FAN motor operates together.
☞ Content to be displayed when checking the self-diagnosis function
When first impressing the voltage the
compressor and FAN work, but they start
operating in 7 minutes after detecting the
temperature (below 10℃ in compartment
F, compartment F defrosting) due to
temporary power cut.
◆Reference : Pulse signal that occurs when motor is spinning
is input at CN75 PIN #6.
This signal is input at MICOM and when the signal is not input
when motor is running, turn off the fan and turn it back on
after 10 seconds.
If the signal still does not turn on, then repeat the process
above 4 more times.
If the signal still does not turn on, restart the motor after 10
minutes.
This function is applied in case the motor restriction is caused
by ice or any other foreign substances around the motor.
Start
Is COMP OFF?
No
Is the voltage DC 7~12V
between the MAIN PCB's GND and
CN75 PIN #3?
No
Turn the power off and after about 7
minutes, turn on the power.
Yes
Does the voltage fluctuate from
DC 7 to 12V between the MAIN PCP's GND and
CN75 PIN #3, and DC 2V or lower between #6 PIN
repeatedly?
Yes
◆ Expected cause
① Faulty FAN-MOTOR
② Check if there's faulty connection between wires.
(MAIN PCB CONNECTOR - TERMINAL part (CN75.①,
③,⑥) refrigerator FAN MONTOR connecting part's faulty
contact, faulty MOTOR connecting WIRE)
③ Check motor spinning pulse input during fan motor
operation
(Please refer to this manual's FAN-MOTOR driving
circuit part)
66
Yes
Operate forced operation
Yes
FAN working properly
No
Replace the MAIN PCB
No