LG LDC22720 Series User manual

CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
REFRIGERATOR
SERVICE MANUAL
MODELS: LDC22720**

CONTENTS
- 2 -
SAFETY PRECAUTIONS
Please read the following instructions before servicing
your refrigerator.
1. Check the refrigerator for current leakage.
2. To prevent electric shock, unplug before servicing.
3. Always check line voltage and amperage.
4. Use standard electrical components.
5. Don’t touch metal products in the freezer with wet
hands. This may cause frostbite.
6. Prevent water from spiling on to electrical elements
or the machine parts.
7. Before tilting the refrigerator, remove all materials
from on or in the refrigerator.
8. When servicing the evaporator, wear gloves to
prevent injuries from the sharp evaporator fins.
9. Service on the refrigerator should be performed by
a qualified technician. Sealed system repair must be
performed by a CFC certified technician,
SAFETY PRECAUTIONS .....................................................................................................
1. SPECIFICATIONS ............................................................................................................
2. PARTS IDENTIFICATION .................................................................................................
3. DISASSEMBLY .................................................................................................................
3.1 Door .............................................................................................................................
3.2 Door switch ..................................................................................................................
3.3 Fan and fan motor ........................................................................................................
3.4 Defrost control assembly ..............................................................................................
3.5 Lamp ............................................................................................................................
3.6 Control Box-Refrigerator ..............................................................................................
3.7 Multi Duct......................................................................................................................
4. ADJUSTMENT ..................................................................................................................
4.1 Compressor ..................................................................................................................
4.2 PTC-Starter ..................................................................................................................
4.3 OLP (Overload Protector) ............................................................................................
4.4 To remove the cover PTC ............................................................................................
5. CIRCUIT DIAGRAM .........................................................................................................
6. TROUBLESHOOTING ......................................................................................................
6.1 Compressor and electrical components ......................................................................
6.2 PTC and OLP ..............................................................................................................
6.3 Other electrical components .......................................................................................
6.4 Service Diagnosis chart ..............................................................................................
6.5 Refrigeration cycle ......................................................................................................
7. DESCRIPTION OF FUNCTION & CIRCUIT OF MICOM .................................................
7.1 Function ......................................................................................................................
7.2 PCB function ...............................................................................................................
7.3 Resistance specification of sensor ..............................................................................
7.4 Troubleshooting ...........................................................................................................
7.5 Main PWB assembly and parts list ..............................................................................
7.6 PWB diagram ..............................................................................................................
8. EXPLODED VIEW AND REPLACEMENT PART LIST ....................................................
2
3
4
6
6
6
7
7
7
7
7
8
8
8
9
9
10
11
11
12
13
14
15
16
16
20
27
28
30
33
35

1. SPECIFICATIONS
- 3 -
HANDLE TYPE VISTA HANDLE
REVERSIBLE DOOR YES
DOOR FINISH PCM
BASKET DOOR NO
LAMP YES(1) 40W/blue
TRAY MEAT YES
SHELF 4EA(FIXED)
MAGIC CRISPER NO
LAMP YES(2) 40W/blue
GUIDE BOTTLE NO
DOOR COOOLING NO
TRAY VEGETABLE Auto-close
ICE TRAY & BANK
SHELF
SPECIFICATIONS
FREEZERREFRIGERATOR
CAPACITY
GENERAL FEATURES
I/B(1EA)
BASKET DOOR 2 1/3+2 2/3+ 1full
REFRIGERANT
MODELS
WIRE(1)
LDC22720**
22CUFT
R134a 115±3

2. PARTS IDENTIFICATION
- 4 -
Ice Bin
Durabase
Divider
Egg Box
Refrigerator Door Rack
Freezer Light
Pull out Drawer
*on some models
B
C
D
A
F
E
Use this section to become more familiar with the parts and features.
NOTE:This guide covers several different models.The refrigerator you have purchased may have some
or all of the items listed below.The locations of the features shown below may not match your model.
G
H
I
J
K
M
N
L
O
P
Q
R
A
B
C
D
E
F
G
H
J
L
N
O
P
K
M
I
Q
R
Ice Tray (Inside of H)*
Optibin Crisper
Keeps fruits and vegetable fresh and crisper
Chef Fresh / Snack Pan
Can Dispenser*
Temperature Control*
Shelves
Refrigerator Light
Digital Sensor Control
Dairy Bin
Design-A-Door
Customcube Icemaker*

- 5 -
A
B
C
D
E
J
K
N
M
L
F
G
HH
I
N
O
Ice Bin
Durabase
Divider
Refrigerator Door Rack
Freezer Light
Pull out Drawer
*on some models
B
C
D
A
F
E
Use this section to become more familiar with the parts and features.
NOTE:This guide covers several different models.The refrigerator you have purchased may have some
or all of the items listed below.The locations of the features shown below may not match your model.
G
H
I
J
K
M
N
L
O
Ice Tray (Inside of F)*
Optibin Crisper
Keeps fruits and vegetable fresh and crisper
Chef Fresh / Snack Pan
Shelves
Refrigerator Light
Digital Sensor Control
Dairy Bin
Design-A-Door
Customcube Icemaker*

3-1 DOOR
Refrigerator Door
1. Remove the hinge cover by pulling it upwards.
2. Loosen the hexagonal bolts attaching the upper hinge to
the body and lift the freezer door.
3. Pull out the door gasket to remove from the door foam
assembly.
Freezer Door
1. Loosen the hexagonal bolts attaching the lower hinge to
the body to remove the refrigerator door only.
2. Pull out the door gasket to remove from the door foam
assembly.
3-2 DOOR SWITCH
1. To remove the door switch, pry it out with a slotted-type
driver, as shown in (Figure 4).
2. Disconnect the lead wire from the switch.
3. DISASSEMBLY
- 6 -
BOLT
HINGE
HINGE COVER
Figure 1
GASKET
Figure 2
LOWER HINGE
BOLT
Figure 3
DOOR SWITCH
LEAD WIRE
Figure 4

3-3 FAN AND FAN MOTOR
1. Remove the freezer shelf. (If your refrigerator has an
icemaker, remove the icemaker first)
2. Remove the grille by pulling it out and by loosening a
screw.
3. Remove the Fan Motor assembly by loosening 2 screws
and disassemble the shroud.
4. Pull out the fan and separate the Fan Motor and Bracket.
3-4 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 72°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 6)
2. Separate the connector with the Defrost Control
assembly and replace the Defrost Control assembly
after cutting the Tie Wrap. (Figure 7)
3-5 LAMP
3-5-1 Refrigerator Compartment Lamp
1. Unplug the power cord from the outlet.
2. Remove refrigerator shelves.
3. Release the hooks on both ends of the lamp shield and
pull the shield downward to remove it.
4. Turn the lamp counterclockwise.
5. Assemble in reverse order of disassembly. Replacement
bulb must be the same specification as the original
(Max. 40 W-2EA).
3-5-2 Freezer Compartment Lamp
1. Unplug refrigerator or disconnect power.
2. Reach behind light shield to remove bulb.
3. Replace bulb with a 40-watt appliance bulb.
4. Plug in refrigerator or reconnect power.
3-6 CONTROL BOX-REFRIGERATOR
1. First, remove all shelves in the refrigerator, than remove
the Refrigerator control Box by loosening 2 screws.
2. Remove the Refrigerator Control Box by pulling it
downward.
3. Disconnect the lead wire on the right position and
separate the lamp sockets.
3-7 MULTI DUCT
1. Remove an upper and
lower Cap by using a flat
screwdriver, and loosen 3
screws. (Figure 11)
2. Disconnect the lead wire
on the bottom position.
- 7 -
FAN
BRACKET
MOTOR
GRILLE
FAN MOTOR
Figure 5
GRILLE ASSEMBLY
Figure 6
DEFROST-CONTROL
ASSEMBLY
Figure 7
Figure 8
Figure 9
CONTROL BOX
COVER LAMP Figure 10
Figure 11

4-1 COMPRESSOR
4-1-1 Role
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 Composition
The compressor includes overload protection. The PTC
starter and OLP (overload protector) are attached to the
outside of the compressor. Since the compressor is
manufactured to tolerances of 1 micron and is hermetically
sealed in a dust and moisture-free environment, use
extreme caution when repairing it.
4-1-3 Note for Usage
(1) Be careful not to allow over-voltage and over-current.
(2) If compressor is dropped or handled carelessly, poor
operation and noise may result.
(3) Use proper electric components appropriate to the
Particular Compressor in your product.
(4) Keep Compressor dry.
If the Compressor gets wet (in the rain or a damp
environment) and rust forms in the pin of the Hermetic
Terminal, poor operation and contact may result.
(5) When replacing the Compressor, be careful that dust,
humidity, and soldering flux don’t contaminate the inside
of the compressor. Dust, humidity, and solder flux
contaminate the cylinder and may cause noise,
improper operation or even cause it to lock up.
4-2 PTC-STARTER
4-2-1 Composition of PTC-Starter
(1) PTC (Positive Temperature Coefficient) is a no-contact
semiconductor starting device which uses ceramic
material consisting of BaTiO3.
(2) The higher the temperature is, the higher the resistance
value. These features are used as a starting device for
the Motor.
4-2-2 Role of PTC-Starter
(1) The PTC is attached to the Sealed Compressor and is
used for starting the Motor.
(2) The compressor is a single-phase induction motor.
Durign the starting operation, the PTC allows current
flow to both the start winding and main winding.
4-2-3 PTC-Applied Circuit Diagram
Starting Method for the Motor
4-2-4 Motor Restarting and PTC Cooling
(1) It requires approximately 5 minutes for the pressure to
equalize before the compressor can restart.
(2) The PTC device generates heat during operation.
Therefore, it must be allowed to cool before the
compressor can restart.
4-2-5 Relation of PTC-Starter and OLP
(1) If the compressor attempts to restart before the PTC
device is cooled, the PTC device will allow current to
flow only to the main winding.
(2) The OLP will open because of the over current
condition. This same process will continue (3 to 5
times) when the compressor attempts to restart until
the PTC device has cooled. The correct OLP must be
properly attached to prevent damage to the
compressor.
Parts may appear physically identical but could have
different electrical ratings. Replace parts by part
number and model number. Using an incorrect part
could result in damage to the product, fire, injury, or
possibly death.
4-2-6 Note for Using the PTC-Starter
(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 PTC,
PTC materials may fail due to breakdown of their
insulating capabilities.
(4) If the exterior of the PTC is damaged, the resistance
value may be altered. This can cause damage to the
compressor and result in a no-start or hard-to-start
condition.
(5) Always use the PTC 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. Using an incorrect part
could result in damage to the product, fire, injury, or
possibly death.
4. ADJUSTMENT
- 8 -
PTC STARTER SEALED
TERMINAL
COMPRESSOR
MOTOR
C
M
SM
36
5
2
S
PTC
N
L1
OVERLOAD PROTECTOR
Resistance Starter Capacitor Running Figure 12

4-3 OLP (OVERLOAD PROTECTOR)
4-3-1 Definition of OLP
(1) OLP (OVERLOAD PROTECTOR) is attached to the
Compressor and protects the Motor by opening the
circuit to the Motor if the temperature rises and
activating the bimetal spring in the OLP.
(2) When high current flows to the Compressor motor, the
Bimetal works by heating the heater inside the OLP,
and the OLP protects the Motor by cutting off the
current flowing to the Compressor Motor.
4-3-2 Role of the OLP
(1) The OLP is attached to the Sealed Compressor used
for the Refrigerator. It prevents the Motor Coil from
being started in the Compressor.
(2) For normal operation of the OLP, do not turn the Adjust
Screw of the OLP in any way.
4-4 TO REMOVE THE COVER PTC
- 9 -
Part
Customer part
number
Lot code/
date code
330 FBYY -S1 BOX98
12345678
Physical
termination
part number
Electrical
characteristics
part number
No. Name
Base, phenolic
(UL 94 V-0 rated)
Movable arm support, plated steel
Stationary contact support,
plated steel
Heater support, plated steel
Heater, resistance alloy
Disc, thermostatic alloy
Movable arm, spring temper
copper alloy
Contact, movable, silver on copper
Contact, stationary, silver on copper
Slug, plated steel
Cover, polyester
(UL 94 V-0 rated)
Pin connector, plated copper alloy
(To engage 2.33/2.66 mm dia. pin)
Quick-connect terminal, brass,
conforms to UL 310, MEMA
DC-2, DIN 46344
(OVERLOAD PROTECTOR cross section)
Figure 13
1)RemovetheCoverBackM/C.
2) Disconnect two housing upper side of comp
connectedin.
3)Loosentwoscrewsoncompbase.
4)UseaL-shapedflaptooltopryoffthecover.
5)Assemblyinreverseorderofdisassembly.

5. CIRCUIT DIAGRAM
- 10 -
4
CON101
BK
MOTOR
1 9
C-FAN
BL PK
STEPPING
6
BO
3
SB
5
RD
2 8
WH
F-FAN
PR
7
YL
PWB(PCB) ASSEMBLY,DISPLAY
1
BL
L1
BK
CON6
10
5
11
BL
FUSE1
RD
L
4
7
68
CON2
RD
CON1
CORD
GN/YL
BK
7
5
(GN)
POWER
YL
BN
PR
YL
8
BN
CON5
PK WH
BO
96
BK
3 1 2
66
5
BN
YL
2
4
10
1
BL
11
BN
2 4
RD
5
9BL
SB
N
7
SB
SUPPLY
3
SB
3
BL
SB
10
BN BL
6
CON4
BK YL
21
WH
8 9
PR
743
RD
CON7
GY
CON8
5
BO
1
1
R-DOOR
DEF-SENSOR
BPERCEPTION S/W
GY
F-DOOR
4
PERCEPTION S/W
PK
GY
4
A
RT-SENSOR
2
D
BO
3BN C
3
2PK
BN
BN
1
BN
SBSB
BL
2
13
CON3
32
SB
BL
7BL F-SENSOR
6BL
WH R-SENSOR
8
WH
5
CON4
GN/YL
CON2
M
HEATER,
BK
WH
ICE SENSOR
1
WH
ICE MAKER
ICE MAKER PART
2
2
WH
WH
MOTOR
1
SHEATH
CON1
1
CON5
CON3
(GN)
WH
1
(98 C)
FUSE-M
I/MAKER
W/VALVE
BK
V
S/W
Cr
RD
PK
22
CAPACITOR PARTCAPACITOR PART
CON6
1
BL
2
1
RD
BK
55
66
44
33
PTC STARTER
Cs
BL
COMP' ACCESSORIES
POWER
PK:PINKYL:YELLOW
BK:BLACK GN:GREEN BN:BROWN
PWB (PCB) ASSEMBLY, ICE MAKER
WH:WHITE
BL
FUSE-M
BL
BA
HEATER,SHEATH
BO
RD
(72 C)
nc
BK
OLP
/YL
SGN
PARTPART
SGN
/YL
M
COMP' EARTHCOMP' EARTH
(GN)(GN) BL
PR
F-LAMP
nc
R-LAMPS
DC
BL
nc
PR:PURPLE
BO:BRIGHT ORANGE BL:BLUE RD:RED
nc
SB:SKY BLUE
GY:GREY
SB
com
FRENCH DOOR HEATER
4
com
DOOR S/W-R DOOR S/W-F
com
PWB(PCB) ASSEMBLY, MAIN
com
4
EG COMP'
46
3
2
5
MC,MQ COMP'
* P.T.C START OPTION
3256
COMP' ACCESSORIES ON CIRCUIT DIAGRAM ARE SUBJECT
*PLUG TYPE, ICE MAKER PART, CAPACITOR PART,
P.T.C START OPTION, DOOR HEATER, RT-SENSOR,
DOOR S/W-R QTY. (1 OR 2), COMP' EARTH PARTAND
TO CHANGE IN DIFFERENT LOCALITIESAND MODEL TYPE.
N
BL
Cr
PTC
COMBO KIT(PTC+OLP)
BK
L
OLP
* ALTERNATIVE COMP' ACCESSORIES

6. TROUBLESHOOTING
- 11 -
6-1 COMPRESSOR AND ELECTRIC COMPONENTS
1
2
3
4
5
2
5
5
3
5
4
5
5
1
43
YES
YES
The range of resistance is between 1~50W (OK)
Not open
4.5~9 W
Open
Open or short
Open or short
YES YES
NO
NO
Power Source.
No Voltage.
(Reated Voltage
±10%)?
Replace OLP.
Reconnect.
Replace
PTC-Starter.
Replace OLP.
Did
compressor
start?
Compressor
is OK
Replace the
compressor
Check connection
condition.
OLP disconnected?
Advise customer that
power supply needs to be
checked by an electrician.
Replace
Compressor.
Supply
voltage rating
with ±10%.
Applied voltage isn't
in range of Rating
Voltage ±10%.
Remove PTC-Starter
from Compressor and
measure voltage
between Terminal C of
Compressor and
Terminals 5 or 6 of PTC.
Check resistance
between M-C, S-C and
M-S in Motor
Compressor.
Check resistance of
two terminals in
PTC-Starter.
Check resistance of two
terminals in OLP.
Check the power supply
under load.
(Compressor attempting
to re-start after being off
for 5 minutes).
Check
resistance of
Motor
Compressor.
Check
resistance of
PTC-Starter.
Check OLP.
Check
starting state.
NO

- 12 -
6-2 PTC AND OLP
65
Shows continuity
Open
Normal operation of
Compressor is
impossible or poor.
Separate PTC-Starter
from Compressor and
measure resistance
between No. 5 and 6
of PTC-Starter with a
Tester.
(Figure 14)
Separate OLP from
Compressor and check
resistance value
between two terminals
of OLP with a Tester.
(Figure 15)
Observation value is
115V/60Hz : 6.8 ±30%
The resistance value
is 0 (short) or
(open).
Check another
electric component.
Replace OLP.
Replace PTC-
Starter.
Figure 14 Figure 15

- 13 -
Not cooling at all
Poor cooling performance
Compressor
doesn't run.
Compressor runs
poorly. Check starting
voltage.
Check for open short or
incorrect resistance readings
in the following components
a. Starting devices
b. OLP
c. Compressor coil
d.Wiring harness
Low voltage.
Short, open, or broken.
Poor contact
or shorted.
Coil open or shorted.
Poor contact
or shorted.
Poor or broken or
open contact.
Shorted.
Lack of capacity.
Replace
indicated component.
Advise customer that
the Power supply
needs to be checked
by an electrician.
Replace
indicated component.
Cause
Check voltage at
starting devices.
Check current flowing
in sub-coil of
Compressor.
Check rating of OLP.
Fan motor
doesn't run.
Heavy frost buildup on
EVAPORATOR.
Wire is open or
shorted.
Coil is shorted
or open.
Open.
Open. Replace
Defrost Heater.
Replace
indicated component.
Replace
indicated component.
Check wiring circuit.
Check Fan Motor.
Check current flow in
the following
components:
Sensor
Fuse-M
Check current flow in
the Defrost Heater.
6-3 OTHER ELECTRICAL COMPONENTS

6-4 SERVICE DIAGNOSIS CHART
- 14 -
COMPLAINT POINTS TO BE CHECKED REMEDY
Other possible problems:
Check if frost forms in
the freezer. Check Components
of the defrosting
circuit.
Check the
refrigeration system.
Check the
Thermistor.
Not
defrosting
The system
is faulty. Perform sealed
system repair.
Replace the
Thermistor.
The operation of
the Thermistor is
incorrect.
No Cooling.
Cools poorly.
Foods in the
Refrigerator
are frozen.
Condensartion or ice
forms inside
the unit.
Condensartion forms
in the Exterior Case.
There is abnormal
noise.
Door does not
close well.
Ice and foods
smell unpleasant.
• Is the power cord unplugged from the outlet?
• Check if the power switch is set to OFF.
• Check if the fuse of the power switch is shorted.
• Measure the voltage of the power outlet.
• Check if the unit is placed too close to the wall.
• Check if the unit is placed too close to the stove,
gas cooker, or in direct sunlight.
• Is the ambient temperature too high or
the room door closed?
• Check if food put in the refrigerator is hot.
• Did you open the door of the unit too often
or check if the door is sealed properly?
• Check if the Control is set to Warm position.
• Is food placed in the cooling air outlet?
• Check if the control is set to colder position.
• Is the ambient temperature below 41°F(5°C)?
• Is liquid food sealed?
• Check if food put in the refrigerator is hot.
• Did you open the door of the unit too
often or check if the door is sealed properly?
• Check if the ambient temperature and humidity
of the surrounding air are high.
• Is there a gap in the door gasket?
• Is the unit positioned in a firm and even place?
• Are any unnecessary objects placed
in the back side of the unit?
• Check if the Drip Tray is not firmly fixed.
• Check if the cover of the compressor enclosure
in the lower front side is taken out.
• Check if the door gasket is dirty with
an item like juice.
• Is the refrigerator level?
• Is there too much food in the refrigerator?
• Check if the inside of the unit is dirty.
• Are foods with a strong odor unwrapped?
• The unit smells of plastic.
• Plug into the outlet.
• Set the switch to ON.
• Replace the fuse.
• If the voltage is low, correct the wiring.
• Place the unit about 4 inches (10 cm) from the wall.
• Place the unit away from these heat sources.
• Lower the ambient temperature.
• Put in foods after they have cooled down.
• Don't open the door too often and close
it firmly.
• Set the control to Recommended position.
• Place foods in the high-temperature section.
(front part)
• Set the control to Recommended position.
• Set the control to Warm position.
• Seal liquid foods with wrap.
• Put in foods after they have cooled down.
• Don't open the door too often and close
it firmly.
• Wipe moisture with a dry cloth. It will disappear
in low temperature and humidity.
• Fill up the gap.
• Adjust the Leveling Screw, and position the
refrigerator in a firm place.
• Remove the objects.
• Fix the Drip Tray firmly in the original position.
• Place the cover in its original position.
• Clean the door gasket.
• Position in the firm place and level the
Leveling Screw.
• Make sure food stored in shelves does not prevent
the door from closing.
• Clean the inside of the unit.
• Wrap foods that have a strong odor.
• New products smell of plastic, but this
will go away after 1-2 weeks.

6-5 REFRIGERATION CYCLE
- 15 -
Troubleshooting Chart
Leakage Detection
YES
YES
Check if compressor
runs.
Check if frost
forms in
Evaporator.
Observe the discharged
amount of Refrigerant.
Inject refrigerant in compressor
and check cooling operation.
Clogged by dust. Gas leakage.
Faulty
Compressor.
Moisture Clog
Check if oil
leaks.
Frost formed normally
Normal amount
None or too much
(Find the leak and repair it)
Frost formed normally
No frost
or frost forms
in inlet only
Check Compressor
PARTIAL Freezer Low flowing sound of A little higher • Refrigerant level is low due
LEAKAGE compartment and Refrigerant is heard and than ambient • to a leak.
Refrigerator don't frost forms in inlet only. temperature. • Normal cooling is possible by
cool normally. • restoring the normal amount of
• refrigerant and repairing the leak.
COMPLETE Freezer Flowing sound of refrigerant Equal to ambient • No discharging of Refrigerant.
LEAKAGE compartment and is not heard and frost isn't temperature. • Normal cooling is possible by
Refrigerator don't formed. • restoring the normal amount of
cool normally. • refrigerant and repairing the leak.
PARTIAL Freezer Flowing sound of refrigerant A little higher • Normal discharging of the
CLOG compartment and is heard and frost forms than ambient • refrigerant.
Refrigerator don't in inlet only. temperature. • The capillary tube is faulty.
cool normally.
WHOLE
Freezer Flowing sound of refrigerant Equal to ambient • Normal discharging of the
CLOG
compartment and is not heard and frost isn't temperature. • Refrigerant.
Refrigerator don't cool. formed.
MOISTURE Cooling operation Flowing sound of refrigerant Lower than • Cooling operation restarts
CLOG stops periodically. is not heard and frost melts. ambient • when heating the inlet of the
temperature. • capillary tube.
COMP- Freezer and Low flowing sound of Alittle higher • Low pressure at high side
RESSION Refrigerator refrigerant is heard and ambient • of compressor due to low
don't cool. frost forms in inlet only. temperature. • refrigerant level.
NO COMP- No compressing Flowing sound of refrigerant Equal to ambient • No pressure in the high
RESSION operation. is not heard and there is temperature. • pressure part of the
no frost. • compressor.
CAUSE TEMPERATURE
OF THE
COMPRESSOR REMARKS
STATE OF
THE UNIT STATE OF THE EVAPORATOR
LEAKAGE
CLOGGEDBYDUST
DEFECTIVE
COMPRESSION
Observe the discharging point of the refrigerant, which may be in the oil discharging part of the compressor and in a hole
in the evaporator.

7. DESCRIPTION OF FUNCTION & CIRCUIT OF MICOM
- 16 -
7-1 FUNCTION
7-1-1 Function
1. When the appliance is plugged in, it is set to for Refrigerator and “4” for freezer.
You can adjust the Refrigerator and the Freezer control temperature by pressing the ADJUST button.
2. When the power is initially applied or restored after a power failure, it is automatically set to “4” & “4”.
7-1-2 Control of freezer fan motor
1. Freezer fan motor has high and standard RPMs.
2.High RPM is used when electricity is first on, for ICE PLUS, and when refrigerator is overloaded.
But standard RPM is used for general purposes.
3. To improve cooling speed and load corresponding speed, the RPM of freezer fan motor shall change from normal
speed to high speed.
4. High speed (2500RPM): initial power on or load corresponding operation, ICE PLUS.
Normal speed (2200RPM): general working conditions.
7-1-3 ICE PLUS
1. The purpose of this function is to intensify the cooling speed of freezer and to increase the amount of ice.
2. Whenever selection switch is pressed, selection/release, the LED will turn ON or OFF.
3. If there is a power cut and the refrigerator is power on again, ICE PLUS function will be canceled.
4. To activate these function you need to press the ICE PLUS key and the LED will turn ON. This function will remain
activated for 24 hrs. The first three hours the compressor and ICE PLUS will be ON. The next 21 hours the freezer
will be controlled at the lowest temperature. After 24 hours or if the ICE PLUS key is pressed again, the freezer will
return to its previous temperature.
5. For the first three hours notice the following cases:
(1) Compressor and freezer fan (HIGH RPM) continuously operate for three hours.
(2) If defrost starts during ICE PLUS, ICE PLUS operates for the rest of time after defrost is completed, when ICE
PLUS operation time is less than 90 minutes
If ICE PLUS operates for more than 90 minutes, the ICE PLUS will operate for one hour after defrost is completed.
(3) If ICE PLUS is pressed during defrost, ICE PLUS LED is on but this function will start seven minutes after defrost
is completed and it shall operate for three hours.
(4) If ICE PLUS is selected whitin seven minutes after compressor has stopped, the compressor (compressor
delaysseven minutes) shall start after the balance of the delay time.
(5) The fan motor in the freezer compartment rotates at high speed during ICE PLUS.
6. For the rest of 21 hours, the freezer will be controlled at the lowest temperature.
7-1-4 REFRIGERATOR LAMP AUTO OFF
1.Toprotecttheriskoflampheat,whenRefrigeratordooropensfor7min.,Refrigeratorlampisautooff.

- 17 -
7-1-5 Alarm for Open Door
1. This feature sounds a buzzer when the freezer or refrigerator door is not closed within 1 minute after it is opened.
2. One minute after the door is opened, the buzzer sounds three times each for ½ seconds. These tones repeat every
30 seconds.
3. The alarm is cancelled when the freezer or the refrigerator is closed while the buzzer sounds.
7-1-6 Buzzer Sound
When the button on the front Display is pushed, a Ding - Dong - sound is produced.
(Refer to the Buzzer Circuit 7-2-4 No. 3)
7-1-7 Defrosting (removing frost)
1.For initial power on or for restoring power, defrosting starts when the compressor running time reaches 4 hours.
2. Defrosting stops if the sensor temperature reaches 46.4°F (8°C) or more. If the sensor doesn’t reach 46.4°F(8°C) in
1 hour, the defrost mode is malfunctioning. (Refer to the defect diagnosis function, 7-1-9.)
3. Defrosting won’t function if its sensor is defective (wires are cut or short circuited)
7-1-8 Electrical Parts Are Turned On Sequentially
Electrical parts such as COMP, defrosting heater, freezer FAN, etc. Are turned on in the following order to prevent
noise and parts damage. Several parts are started at the same time at initial power on and are turned off together
when TEST is completed.
Closed Open Closed Open
Closed
3 Times 3 Times 3 Times 3 Times
Within 1 min. 1 min. 30 sec 30 sec 30 sec
Freezer Door
or Refrigerator
Door
Buzzer
OPERATING ORDERS
Initial power on
Temperature of Defrosting
Sensor is 45°C or more
(when unit is newly
purchased or when moved)
POWER
ON In ½ second COMP ON In ½ second Freezer FAN ON In ½ second Cooling FAN ON
Temperature of defrosting
sensor is lower than 45°C
(when power cuts, SERVICE)
POWER
ON In ½ second Defrosting heater ON In 10 second Defrosting heater OFF
In ½ second COMP
ON In ½ second Freezer FAN ON In ½ second Cooling FAN ON
Reset to normal operation
from TEST MODE Total Load
OFF In 7 minute COMP ON In ½ second Freezer FAN ON In ½ second Cooling FAN ON

- 18 -
7-1-9 Defect Diagnosis Function
1. Automatic diagnosis makes servicing the refrigerator easy.
2. When a defect occurs, the buttons will not operate; but the tones, such as ding- will sound.
3. When the defect CODE removes the sign, it returns to normal operation (RESET).
4. The defect CODE shows on the Refrigerator and Freezer Display.
ERROR CODE on display panel
NO ITEM ERROR CODE CONTENTS REMARKS
1
2
3
4
Failure of freezer
sensor
Failure of
Refrigerator sensor
Failure of defrost
sensor
Poor of defrost
Cut or short circuit wire
Cut or short circuit wire
Cut or short circuit wire
Inspect Connecting
wires on each sensor
Snapping of defrost
heater or Temperature
fuse, pull-out of
Connector (indicated
minimum 2 Hours
after failure occurs)
All off
All off
All off
All off
LED OFF LED ON
1 hours later after
starting defrost, If
sensor doesn’t be
over 46ºF (8ºC)
5Failure of BLDC fan
motor at freezing
compartment
All off If there is no fan motor
signal, for more than
fan motor.
Poor motor, hocking to
wires of fan, contact of
structures to fan,
snapping or short of lead
115 seg. in operation

- 19 -
7-1-10 TEST MODE
1. The Test mode allows checking the PCB and the function of the product as well as finding out the defective part in
case of an error.
2. While in the test mode, the function control button is not recognized, but the recognition tone (beep - ) sounds.
3. After exiting the test mode, be sure to reset by unplugging and then plugging in the appliance.
4. If an error, such as a sensor failure, is detected while in the test mode, the test mode is cleared and the error code
is displayed.
5. While an error code is displayed, the test mode will not be activated.
NOTE: LED CHECK MODE: When the refrigerator temperature control and the dreezer temperature control button at
The same time are hold for 1 second or longer, every LED on the display turns on at the same time, when the
Button are released, the previous mode is restored.
*Freezer Fan RPM Variable Check:
In case the freezer fan is in operation when the ADJUST key in Refrigerator and Freezer Temp. Control are pressed
for more than one second at the same time freezer fan RPM changes. (For example if high speed, to normal speed
or if normal speed, to high speed for 30 seconds)
After 30 seconds, it turns to its original RPM.
*Demonstration MODE:
1. When the ULTRA ICE key and ADJUST key of refrigerator temperature control are pressed for more than 3
seconds at the same time temperature’s it converts to demonstration mode.
2. In this status, each LED is rotated with 1 second interval.
3. In this status, all Loads are off (Compressor/ Fan/ Damper/ Heater)
(Even is Demonstration Mode, the refrigerator Lamp automatic off function works normally and can be
demostrated).
4. It reset if you do again as clause.
MODE MANIPULATION CONTENTS REMARKS
TEST1
TEST2
Reset
Push ICEPLUS key and
ADJUST key of Freezer
temperature at the same
time over 3 seconds. Or
press TEST S/W one time
in the Main PCB board.
Push ICEPLUS key and
ADJUST key of Freezer
temperature at the same
time over 3 seconds being
in TEST MODE1. Or press
TEST S/W one time being
in TEST MODE 1.
Push ICEPLUS key and
ADJUST key of Freezer
temperature at the same
time over 3 seconds being
in TEST MODE2. Or press
TEST S/W one time being
in TEST MODE 2.
1.-Continuous operation of the
COMPRESSOR
2.Continuous operation of the freezer fan
3.Stepping DAMPER OPEN
4.Defrosting Heater OFF
5.Every DISPLAY LED ON
1.COMP OFF
2.Freezer FAN OFF
3.Stepping DAMPER CLOSE
4.Defrosting Heater ON
5.DISPLAY LED 1,3,5,7 ON
Reset after 5 minutes
Reset if the temperature
of the defrosting sensor
is 46°F (8°C) or more
Reset to the previously setting before
TEST MODE
The Compressor will
start after a 7-minute
Delay
MODE MANIPULATION CONTENTS REMARKS
TEST1
TEST2
Reset
Push ICEPLUS key and
ADJUST key of Freezer
temperature at the same
time over 3 seconds. Or
press TEST S/W one time
in the Main PCB board.
Push ICEPLUS key and
ADJUST key of Freezer
temperature at the same
time over 3 seconds being
in TEST MODE1. Or press
TEST S/W one time being
in TEST MODE 1.
Push ICEPLUS key and
ADJUST key of Freezer
temperature at the same
time over 3 seconds being
in TEST MODE2. Or press
TEST S/W one time being
in TEST MODE 2.
1.-Continuous operation of the
COMPRESSOR
2.Continuous operation of the freezer fan
3.Stepping DAMPER OPEN
4.Defrosting Heater OFF
5.Every DISPLAY LED ON
1.COMP OFF
2.Freezer FAN OFF
3.Stepping DAMPER CLOSE
4.Defrosting Heater ON
5.DISPLAY LED 1,3,5,7 ON
Reset after 5 minutes
Reset if the temperature
of the defrosting sensor
is 46°F (8°C) or more
Reset to the previously setting before
TEST MODE
The Compressor will
start after a 7-minute
Delay

7-2 PCB FUNCTION
7-2-1 Power Circuit
The secondary part of the TRANSFORMER is composed of the power supply for the display, the BLDC FAN Motor drive
(15.5 V), the relay drive (12 Vdc) and the MICOM and IC (5 Vdc).
The voltage for each part is as follows:
VA1 is a part for preventing over voltage and noise. When 385V or higher power is applied, the inside elements are short-
circuited and broken, resulting in blowout of the fuse in order to protect the elements of the secondary part of the
TRANSFORMER.
- 20 -
PART VA 1 CE 3 CE 4 CE 5
VOLTAGE 115 Vac 12 Vdc 15.5 Vdc 5 V