LG LFX28968SW Service Manual - Page 57

Check B

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12-2 Check B B1. LED blinks once, then repeats (FCT0 Fault) Protection Logic Blink OFF Blink OFF - Purpose: Detecting motor current and voltage error - Check voltage at point A (Motor Voltage), point B (Motor Current) and Point C (Capacitor Voltage) when compressor is off. - Spec: Points A, B, & C 2.5V ± 0.3V GND Voltage Protection logic Check B Blink 1 time (FCT 0) Check B1 Out of spec? (2.2 - 2.8V) N Reset Power Y Replace Driver PCB B A C B2. LED blinks two times, then repeats (Stroke Trip) Protection Logic Blink Blink OFF Blink Blink OFF - Purpose: Prevent abnormally long piston strokes. - Case 1. If compressor doesn't work and LED blinks - Cause: Possibly harness from compressor to PCB might be defective. - Case 2. If compressor works intermittently and LED blinks - Cause: Condenser Fan or Freezer Fan is not running. Sealed system problem such as moisture restriction, restriction at capillary tube or refrigerant leak. - Logic: Compressor is forced to off and then tries to restart after 1 minute. Protection logic Check B Blink 2 times (Stroke Trip) Check B2 N Fix Harness Compressor Doesn't work Replace Driver PCB N Fix Cycle OK NG Cycle Check E Y Y Harness Y Connecting Check C Compressor Y Works Intermittently Repeat N Check Procedure Stroke Trip Occur? Reset Power - 57 - Capacitor Spec. Check C Y Compressor Damage Check C Y N Replace Capacitor N Replace Compressor

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- 57 -
12-2 Check B
B1. LED blinks once, then repeats (FCT0 Fault)
-
Purpose: Detecting motor current and voltage error
-
Check voltage at
point A
(Motor Voltage),
point B
(Motor Current) and
Point C
(Capacitor
Voltage) when
compressor is off
.
- Spec:
Points A, B,
&
C 2.5V
±
0.3V
Protection Logic
Blink
OFF Blink
OFF
Y
N
Protection
logic
Check B
Blink 1 time
(FCT 0) Check B1
Out of spec?
(2.2 - 2.8V)
Reset Power
Replace Driver PCB
B2. LED blinks two times, then repeats (Stroke Trip)
Protection Logic
Blink
Blink OFF
Blink
Blink
OFF
Y
Y
Y
Y
Protection
logic
Check B
Blink 2 times
(Stroke Trip) Check B2
Compressor
Doesn’t work
Y
N
Compressor
Works Intermittently
Capacitor
Spec.
Check C
Compressor
Damage
Check C
Replace
Capacitor
Replace
Compressor
N
N
Reset
Power
Stroke Trip
Occur?
Y
Repeat
Check Procedure
Harness
Connecting
Check C
Fix Harness
N
N
Cycle
Check E
Fix
Cycle
Replace
Driver PCB
OK
NG
-
Purpose: Prevent abnormally long piston strokes.
-
Case 1. If compressor doesn’t work and LED blinks - Cause: Possibly harness from compressor to PCB might be
defective.
-
Case 2. If compressor works intermittently and LED blinks - Cause: Condenser Fan or Freezer Fan is not running. Sealed
system problem such as moisture restriction, restriction at capillary tube or refrigerant leak.
-
Logic: Compressor is forced to off and then tries to restart after 1 minute.
GND
Voltage
A
B
C