LG LFX28979 SERIES User manual

CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
MODEL : LFX28979**
COLOR : STAINLESS(ST)
WESTERN BLACK(WB)
SUPER WHITE(SW)
REFRIGERATOR
SERVICE MANUAL

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CONTENTS
SAFETY PRECAUTIONS ....................................................................................................................................................... 2
1. SPECIFICATIONS ............................................................................................................................................................. 3
2. PARTS IDENTIFICATION ..................................................................................................................................................4
3. DISASSEMBLY ............................................................................................................................................................ 5-16
REMOVING AND REPLACING REFRIGERATOR DOORS ..............................................................................................5
DOOR ................................................................................................................................................................................ 6
DOOR ALIGNMENT ...........................................................................................................................................................7
FAN AND FAN MOTOR(EVAPORATOR) ..........................................................................................................................7
DEFROST CONTROL ASSEMBLY ....................................................................................................................................7
LAMP ..................................................................................................................................................................................8
MULTI DUCT ......................................................................................................................................................................8
MAIN PWB ..........................................................................................................................................................................9
DISPENSER ...................................................................................................................................................................... 9
DISPLAY PCB ................................................................................................................................................................... 9
ICE BUTTON ASSEMBLY ................................................................................................................................................. 9
WATER BUTTON ASSMEBLY ........................................................................................................................................ 10
ICE CORNER DOOR REPLACEMENT ........................................................................................................................... 10
ICEMAKER REPLACEMENT ..................................................................................................................................... 10-11
SUB PWB FOR WORKING DISPENSER ....................................................................................................................... 11
CAP DUCT MOTOR REPLACEMENT ............................................................................................................................ 11
HOW TO REMOVE A ICE BIN ........................................................................................................................................ 12
HOW TO INSERT A ICE BIN ........................................................................................................................................... 12
HOW TO REMOVE AND REINSTALL THE PULLOUT DRAWER ............................................................................. 13-14
WATER VALVE DISASSEMBLY METHOD .................................................................................................................... 15
FAN AND FAN MOTOR DISASSEMBLY METHOD ........................................................................................................ 15
DRAWER REMOVAL ...................................................................................................................................................... 16
4. ADJUSTMENT ................................................................................................................................................................ 17
5. CIRCUIT DIAGRAM ........................................................................................................................................................ 18
6. TROUBLESHOOTING .................................................................................................................................................... 19
7. PCB PICTURE ........................................................................................................................................................... 20-21
8. Troubleshooting With Error Display ....................................................................................................................... 22-30
9. Troubleshooting Without Error Display ................................................................................................................. 31-39
10. Reference .................................................................................................................................................................. 40-43
11. COMPONENT TESTING INFORMATION ................................................................................................................. 44-52
12. COMPRESSOR TROUBLESHOOTING ................................................................................................................... 53-64
13. ICEMAKER OPEARTING AND TROUBLE SHOOTING METHOD ......................................................................... 65-68
14. DESCRIPTION OF FUNCTION & CIRCUIT OF MICOM ........................................................................................... 69-72
SAFETY PRECAUTIONS
Please read the following instructions before servicing your refrigerator.
1. Unplug the power before handling any elctrical componets.
2. Check the rated current, voltage, and capacity.
3. Take caution not to get water near any electrical components.
4. Use exact replacement parts.
5. Remove any objects from the top prior to tilting the product.

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1. SPECIFICATIONS
1-1 LFX28979**
DOOR DESIGN
DIMENSIONS (inches)
NET WEIGHT (pounds)
COOLING SYSTEM
TEMPERATURE CONTROL
DEFROSTING SYSTEM
DOOR FINISH
HANDLE TYPE
INNER CASE
INSULATION
ITEMS
Side Rounded
35 3/4 X 35 3/8 X 69 3/4 (WXDXH) 28cu.ft.
155kg (342lb)
Fan Cooling
Micom Control
Full Automatic
Heater Defrost
PCM, VCM, Stainless
Bar
ABS Resin
Polyurethane Foam
SPECIFICATIONS
●28 cu.ft.
VEGETABLE TRAY
COMPRESSOR
EVAPORATOR
CONDENSER
REFRIGERANT
LUBRICATING OIL
DEFROSTING DEVICE
ITEMS
Clear Drawer Type
Linear
Fin Tube Type
Spiral Condenser
R-134a (140 g)
ISO10 (280 ml)
SHEATH HEATER
LED Module(24)
Bulb Lamp
SPECIFICATIONS
LAMP REFRIGERATOR
FREEZER
●DIMENSIONS
Depth w/ Handles
Depth w/o Handles
Depth w/o Door
Depth (Total with Door Open)
Height to Top of Case
Height to Top of Door Hinge
Width
Width (door open 90 deg. w/o handle)
Width (door open 90 deg. w/ handle)
A
B
C
D
E
F
G
H
I
35 3/8 in
32 7/8 in
29 in
47 5/8 in
68 3/8 in
69 3/4 in
35 3/4 in
39 1/4 in
44 1/4 in
Description LFX28979**

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2. PARTS IDENTIFICATION
LED Interior Lamps
The interior lamps light
up the inside ot the
refrigerator.
Can Storage Bin
Used to preserve
chilled food drinks.
Durabase Divider
Ice Bin
Auto Icemaker
Fixed Door Bins.
Dairy Product Bin
Modular Door Bins
Pullout Drawer
Durabase
Refrigerator Shelves
The shelves in your
refrigerator are
adjustable to meet your
individual storage
needs.
Refrigerator Interior
Key Parts and Components

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Water Filter
SpacePlus Ice System
Automatically produces
80-130 ice cubes in a
24-hour period.
Auto Closing Hinge
The refrigerator doors
and freezer drawers close
automatically when you
push them slightly.
(The door only closes
automatically when it is
open at an angle of less
than 30°.)
Mullion
Folds in when the
left door is opened.
Smart Diagnosis Speaker
Hold your phone to this speaker when
activating Smart Diagnosis. Refer to
the Smart Diagnosis section for more
details.
Special Features
Crispers
Controls humidity and
helps vegetables and
fruit to stay crisp.
Glide’N’Serve
Allows you to store
food items at a different
temperature than the regular
refrigerator area.

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3. DISASSEMBLY
3-1 REMOVING AND REPLACING REFRIGERATOR DOORS
●Removing Refrigerator Door
CAUTION: Before you begin, unplug the refrigerator. Remove food and bins from doors.
▶Left Door -FIG. 2
1. Disconnect water supply tube by pushing back on the disconnect ring (3).-FIG. 1
2. Open door. Loosen top hinge cover screw (1).
Use flat tip screwdriver to pry back hooks on front underside of cover (2). Lift up cover.
3. Disconnect door switch wire harness and remove the cover.
4. Pull out the tube.
5. Disconnect all 3 wiring harnesses (4). Remove the grounding screw (5).
6. Rotate hinge lever (6) counterclockwise. Lift top hinge (7) free of hinge lever latch (8).
7. Lift door from middle hinge pin and remove door.
8. Place the door with the insides facing up, on a not scratch surface.
CAUTION: When lifting hinge free from the latch, be careful that door does not fall forward.
▶Right Door -FIG. 3
1. Open the door, remove 1 screw on the top of the hinge cover. Loosen top hinge cover screw (1). Lift up cover (2).
2. Disconnect door switch wire harness and remove the cover.
3. Rotate hinge lever (3) clockwise. Lift top hinge (4) free of hinge lever latch (5).
4. Lift door from middle hinge pin and remove door.
5. Place the door with the insides facing up, on a not scratch surface.
CAUTION: When lifting hinge free from the latch, be careful that the door does not fall forward.
Correct Incorrect
Figure 2 Figure 3
Figure 1
1) Insert the tube until you can see only one of
the lines printed on the tube.
2) After inserting, pull the tube to ascertain that
it is secure.
3) Assemble clip.

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1. Remove gasket
Pull gasket free from gasket channel on the four
remaining sides of door.
3-2 DOOR
●Mullion Removal
1. Remove 2 screws.
●Door Gasket Removal
2. Lift Mullion up carefully.
3. Disconnect wire harness.
●Door Gasket Replacement
1. Insert gasket into channel
Press gasket into channels on the four remaining
sides of door.
2. Insert mullion into the channel.
Insert the cover assembly into bracket, door.
●Mullion Replacement
1. Connect wire harness.
3. Assemble 2 screws.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8

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*Ice Fan Scroll Assembly Replacement
1) Remove the plastic guide on the left side, using a
phillips screwdriver to remove the screws.
2) Pull off the sensor cover.
3) Remove the grill cover.
4) Gently pull on the grill assembly to remove.
5) Disconnect the wiring harness.
6) Remove all screws on the scroll assembly.
(1) (2)
(3) (4)
(5) (6)
3-5 DEFROST CONTROL ASSEMBLY
Defrost Control assembly consists of Defrost Sensor and
FUSE-M.
The Defrost Sensor works to defrost automatically. It is
attached to the metal side of the Evaporator and senses its
temperature. At 46F(8°C), it turns the Defrost Heater off.
Fuse-M is a safety device for preventing over-heating of
the Heater when defrosting.
1. Pull out the grille assembly. (Figure 12)
2. Separate the connector with the Defrost Control
assembly and replace the Defrost Control assembly after
cutting the Tie Wrap. (Figure 13)
Figure 12 Figure 13
GRILLE ASSEMBLY DEFROST-CONTROL
ASSEMBLY
3-3 Door Alignment
If the space between the door are uneven,
follow the instructions to align them.
Remove the Base Grillie. Turn the leveling legs counter
clock wise to raise or clock wise to lower the height of the
front of the refrigerator by using flat blade screw driver or
11/32" wrench. Use the wrench (Included with the User
Manual) to adjust the bolt in the door hinge to adjust the
height. (CCW to raise or CW to lower the height.)
3-4 FAN AND FAN MOTOR(EVAPORATOR)
1. Remove the freezer drawer. (If your refrigerator has an
icemaker, remove the icemaker first)
2. Remove the plastic guide for slides on left side by
unscrewing phillips head screws.
3. Remove the grille by removing 4 screws and pulling the
grille forward.
4. Remove the Fan Motor assembly by loosening 3 screws
and disassembling the shroud.
5. Pull out the fan and separate the Fan Motor and Bracket.
FAN MOTOR
BRACKET
MOTOR
Shroud
Figure 9
Figure 10
Figure 11

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Figure 18
1. Unplug refrigerator power cord form outlet.
2. Remove screw with driver.
3. Grasp the cover Lamp, pull the cover downward.
3-6-2 Freezer Compartment Lamp
3-7 MULTI DUCT
1. Romove the upper and
lower caps with a flat
screwdriver and remove
2 screws.
(Figure 19)
2. Disconnect the lead wire
on the bottom position.
Figure 19
Figure 14
Figure 15
3-6 LAMP
Unplug, or disconnect power at the circuit breaker.
If necessary, remove top shelf or shelves.
1) Release 2 screws.
2) Hold both ends and pull down to remove.
3-6-1 Refrigerator Compartment Lamp
Figure 16
4) Use a flat tool as shown below to remove the lamp
cover.
Figure 17
5) To remove the LED assembly, pull apart the cover.
Cover, lamp
Case, lamp
LED, Assembly
3) To remove the lamp case and cover, release 2 screws
as shown.

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3-8 MAIN PWB
1) Loosen 3 screws on the PWB cover.
3-9 DISPENSER
1) Pull out the drain
2) Remove the PWB cover
3) Disconnect wire harness and replace the main PWB in
the reverse order of removal.
3-10 DISPLAY PCB
As shown below, remove 1 screw on the PCB fixing screw.
Remove the display PCB fixing screw.
3-11 ICE BUTTON ASSEMBLY
1) Remove the 1 screw holding the lever.
2) Remove the spring from the hook.
3) Push and pull on the tab to remove.
CAUTION: When replacing the dispenser cover make
sure the lead wire does NOT come off and the water line
is not pinched by the dispenser.
Case, PCB
Button Lever
Display PCB
Figure 20
Figure 21
Figure 22
Figure 23 Figure 24
Figure 25
Figure 30
Figure 28
Case, PCB Display PCB
Figure 29
Figure 28
2) Use these 2 holes to pull
out the bottom
3) If nozzle is interfered with button, push and pull out the
bottom of button and then pull out the right side.
4) Holding the inner side of
the dispenser pull
forward to remove.
5) Remove the
lead wire.
Figure 26 Figure 27

- 11 -- 11 -
3-13 ICE CORNER DOOR REPLACEMENT
1) Loosen the front screw as shown in the picture.
2) Lift up the hinge with one hand.
3) Pull out the Ice Corner Door with the other hand.
3-12 WATER BUTTON ASSMEBLY
1) Remove screws.
2) Grasp the Button assembly and lift.
Button Lever
hinge
3-14 ICEMAKER REPLACEMENT
1) Remove 4 screws as shown.
2) Grasp the bottom of motor cover assembly and pull
slowly.
3) Disconnect wire harness from wall of compartment.
In-door
motor
Figure 31
Figure 32
Figure 35
Figure 33
Figure 34

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3-16 CAP DUCT MOTOR REPLACEMENT
1) Separate the Housing of the Cap Duct Motor.
3) When replacing the motor, check the position of the door
duct and the link for proper fit.
Link
Duct Door
Cap Duct Motor
NG Position
2) Unscrew 3 screws to disassemble the motor.
4) Insert 2 screws.
5) Push housing aside.
3-15 SUB PWB FOR WORKING DISPENSER
1) Disconnect the wire harness.
2) Remove 1 screw from PWB and replace with new PWB.
CAUTION: Make sure that the motor housing is taped to
the mold, if not positioned correctly the cover will not fit
properly.
Figure 36
Figure 37
Figure 38
Figure 43
Figure 42
Figure 41
Figure 40
Figure 39

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3-17 HOW TO REMOVE A ICE BIN
1) Grip the handles, as shown.
2) Tilt and lift slightly as shown.
3-18 HOW TO INSERT A ICE BIN
1) Insert the Ice Bin, slightly tilting to avoid touching the
Icemaker. (Especially, Ice-Detecting Sensor)

3) Remove ice bin slowly.
Figure 44
Figure 45
Figure 46
Figure 47

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3-19 HOW TO REMOVE AND REINSTALL THE PULLOUT DRAWER
3-19-1 Follow Steps to Remove
Step 1) Open the freezer door.
Step 3) Remove the two screws from the guide rails (one
from each side).
Step 2) Remove the lower basket.
Step 4) Removal of the freezer door is done by lifting clear
of the rail support.
Fully extend both rails.
Step 6) Remove 2 screws of both side of supporter covers
tv and disassemble the supporter cover tv.
Step 5) Remove only 1 screw of gearice, and disassemble
the bar and gearice

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3-19-2 Follow Steps to Reinstall
Step 1) Insert both side of supporter cover tv into
connector rails, and then screw them.
Step 3) Put gear ice assembled with the bar by screw into
connector rail’s hole.
Step 4) Insert opposite gear ice into connector rail and
screw them
Step 6) Reinstall the freezer door by inserting the rail tabs
into the guide rail.
Step 8) Reinstall the lower basket, and close the freezer
door.
Step 5) The rail system will align itself by pushing the rails
all the way into the freezer section.
Pull the rails back out to full extension.
Step 7) Reinstall the two screws into the guide rails
(one from each side).
Step 2) ①Assemble a bar and gear ice with screw.
②Push the otherside of the gear to inside of the
bar.
* Assemble them like as pictures

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3-20 WATER VALVE DISASSEMBLY METHOD
1) Turn off the water to unit. Remove the waterline from the
valve.
3-21 FAN AND FAN MOTOR DISASSEMBLY
METHOD
1) Remove screws for the Drain Pipe Assembly and the 1
connected to the Motor Cover.
2) Remove cover and 1 screw from the valve.
3) Separate the housing and remove the valve.
4) Remove the clip, and press the collet to separate the
tube from the connector. Note: there maybe some water
in the line.
Mechanical Cover
Housing
MOTOR COVER
2) Separate the Fan Assembly and Motor, turn counter
clockwise to remove from the motor shaft.
FAN ASSEMBLY MOTOR
Assemble in reverse order. Taking care to avoid.
1. Do not to bend the tube during assembly.
2. Press the Water Dispenser button letting water pour out,
this checks for any leaks in the tube connection, this may
vary depending on the water pressure
( about 2 minutes.).
Figure 60
Figure 61
Figure 62
Figure 63
Figure 64
Figure 65

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3-22 Drawer Removal
Fully extend the drawer and lift from the front pulling straight out.
To install the drawer back into the frame, tilt the front sightly and pushingt back into place.
Figure 66
Figure 67

- 18 -
4-2-3 Compressor protection logic
Since linear Comp conducts linear reciprocating motion,
we have protection logic for compressor, motor and PCB
as the below.
-Stroke Trip
During the operation, if stroke is above the target value,
decrease the target volt by 3V.
-Current Trip
Current trip is set in order to protect compressor
mechanical part and drive from the overcurrent that might
arise during the operation.
Check the current for every 416.7us and if the Trip
exceeds 1.86Arms more than three times at Comp ON,
forcibly stop and restart six minutes later.
-Lock Piston Trip
If stroke is under 5mm even if the current is more than
14Arms, Take it as ‘piston lock’ and restart after 2’30” of
Comp OFF. Check the current and stroke for every
416.7us and if the condition fits more than three times at
Comp ON, the Trip occurs.
-IPM fault Trip
It occurs if FO signal received from IPM is LOW. For
every 416.7us, check whether FO signal is LOW. The trip
occurs if it is found three times during the five
periods(83ms).
4. ADJUSTMENT
4-1-1 Role
4-1 COMPRESSOR
The compressor intakes low temperature and low pressure
gas from the evaporator of the refrigerator and compresses
this gas to high-temperature and high-pressure gas. It then
delivers the gas to the condenser.
4-1-2 Note for Usage
(1) Be careful not to allow over-voltage and over-current.
(2) Do not drop or handle carelessly.
(3) Keep away from any liquid.
If liquid such as oil or water enters the Cover PTC
Compressor may fail due to breakdown of their
insulating capabilities.
(4) Always use the Parts designed for the compressor and
make sure it is properly attached to the compressor.
Parts may appear physically identical but could have
different electrical ratings. Replace parts by part number
and model number. Use only approved substitute parts.
4-1-3 Remove the cover PTC
(1) Remove the Cover Back M/C
(2) Loosen two screws on comp base
(3) Use a L-shaped flap tooll to pry off the cover
(4) Assembly in reverse order of disassembly

- 19 -
5. CIRCUIT DIAGRAM
LFX28978**

- 20 -
6. TROUBLESHOOTING
6-1 Error Code Summary
WARNING: When checking Resistance values, make sure to
turn off the power, and wait for the voltage to
discharge.
NOTE) Within 3 hours after the error : Press the Ice Plus button and Freezer button simultaneously
3 hours after the error : All errors, except for "Er rt", "Er SS",
"Er IS(except for Icing sensor)", "Er gF", "Er It" error, are displayed.
"Er IS" which is displayed without input of user is the error of Icing Sensor.
NO Error Detection
Category
1Normal None Normal operation of Display
2Freezer Sensor
Error Er FS Short or Disconnection of Freezer Sensor
3Refrigerator
Sensor Error Er rS Short or Disconnection of Refrigerator Sensor
Check each sensor at it’s
connector.
Error Generation Factors Remark
Error Display
4Defrosting
Sensor Error Er dS Short or Disconnection of Defrosting Sensor
5Icing Sensor
Error Er IS
Short or disconnection of
the sensor about Ice maker
(Icing sensor, Ice maker
sensor)
6Pantry sensor
error Er SS Short or Disconnection
of Pantry Sensor
10 Poor Defrosting Er dH
Even though it is passed
1 hour since then Defrosting,
if Defrosting sensor is not
over 46°F(8°C), it is caused
Temperature Fuse
Disconnection, Heater
disconnection, DRAIN Jam,
Poor Relay for Heater
8Ice maker kit
defect Er It Other Electric system error
such as moter, gear, Hall IC,
operation circuit within I/M kit
When the ice does not drop
even when the I/M Test S/W
is pressed
9Flow
Meter(Sensor)
Defect
Er gF Error of flow meter or water
input or low water pressure
Error of flow meter or water
input or low water pressure or
flow meter connection
11
Abnormality of
BLDC FAN Motor
for Ice Making
Er IF
It is caused when feedback
signal isn’t over 65 seconds
during BLDC FAN motor
operating
Poor BLDC Motor connection,
DRIVE IC, and TR
12 Abnormality of
BLDC FAN Motor
for Freezer
Er FF
It is caused when feedback
signal isn’t over 65 seconds
during BLDC FAN motor
operating
Poor BLDC Motor connection,
DRIVE IC, and TR
14
Abnormality of
BLDC FAN Motor
for Mechanic
Room
Er CF
It is caused when feedback
signal isn’t over 65 seconds
during BLDC FAN motor
operating
Poor BLDC Motor connection,
DRIVE IC, and TR
15 Communication
Error Er CO
Communication Error
between Micom of Main PCB
and Display Micom
Poor Communication
connection,Poor TR of
Transmitter and Receiver
Tx/Rx between display and
main board.
7Room Temp
Sensor Error Er rt Short or Disconnectoin of
Room temp.sensor
13
Abnormality of
BLDC FAN
MOTOR For
Refrigerator
Er rF
It is caused when feedback
signal isn’t over 65 seconds
during BLDC FAN motor
operating
Poor BLDC Motor connection,
DRIVE IC, and TR
Freezer
Temperature
(Error code )
Refrigerator
Temperature
(Error code )