LG GR-J303T Service Manual

CAUTION

PLEASE READ CAREFULLY THE SAFETY PRECAUTIONS OF THIS MANUAL
BEFORE CHECKING OR OPERATING THE REFRIGERATOR.

KIMCHI REFRIGERATOR

SERVICE MANUAL

http://biz.lgservice.com

MODEL : GR-J303T*

1. Firstly check that there is electrical leakage in the main body of the product.

2. Perform work always after removing the power plugs in handling with the part where electricity conducts through.

3. Wear a rubber gloves(insulation gloves) for preventing electrical shock accident in case of testing with power on.

4. Always check rated current, voltage and capacity in using the instruments.

5. Exercise care so that water does not enter into electrical parts around the machine room.

6. Take care so that things should not fall down by removing them cleanly on the product when leaning the product forward
or backward. Especially, take care of thin things (glass panels, books).

7. Ensure to consult the repair and maintenance center shop when the cold storage cycle is damaged (to prevent that gas
inside of the cycle gets a room dirty).

SAFETY INSTRUCTIONS

1. Product Specifications ..........................................................................................................................................................3

2. Circuit Diagram ....................................................................................................................................................................5

3. MICOM Function and Explanations of Circuits ....................................................................................................................6

4. Exploded View and Service Parts List ................................................................................................................................34

CONTENTS

- 2 -

1-1. GR-J303T*

1. PRODUCT SPECIFICATIONS

Rating

Defrosting Device

Dimensions (mm)

Net Weight

Motor Power Consumption

Cooling Method

Insulation

Evaporation Dish

Basket

Storage Container

Drawer

Shelf

Flap Door

Low temperature Catalyst

Deodorization

115V/60Hz 115V/60Hz

300 L 300 L
156 L 156 L

144

L

144

L

667(W) X 670.4(D) 1775(H)mm 667(W) X 670.4(D) 1775(H)mm

113 Kg 103 Kg

138W 138W

Indirect Cooling System

Force
Automation
Automation

Force

Light Polyurethane Foam

1 EA (Behind)

2 EA

14 EA 8 EA

1 EA 3 EA
3 EA 1 EA

1 EA

2 EA

LC62LBCM

Fin Tube Type

Fin Tube Type

Wire Condenser, Back Plate Condenser

R134a (160 g) R134a (160 g)

α10G 310cc α10G 311cc

Heater, Sheath

Capacity

Defrosting

System

Cooling

Cycle

Net Capacity

Top Compartment

Middle/Bottom

Compartment

Method

Start

End

Evaporation

Compressor

Evaporator of

Top Compartment

Evaporator of

Middle Compartment
Condenser 2 EA

Refirgerant

Refrigerant Oil

ITEMS SPEC SPEC

MODEL GR-J303TG GR-J303TS

- 3 -

- 4 -

P6R8MD P6R8MD

4TM314TFB 4TM314TFB

Ø110 Fan Ø110 Fan
Ø110 Fan Ø110 Fan

Ø110 Fan Ø110 Fan

115 V 140 W 115 V 140 W

115 V 180 W(Half wave 90 W) 115 V 180 W(Half wave 90 W)

120 V(UL) 7 W 120 V(UL) 7 W
Cutted at 70 °C Cutted at 70 °C
Cutted at 70 °C Cutted at 70 °C

250 V 9 A 250 V 9 A

14㎌ / 250Vac 14㎌ / 250Vac

Electrical

System

Rating

Defrosting

Heater

Top

Middle

P.T.C

Overload Protector

Fan Motor(Top)

Fan Motor(Middle)

Condenser

Cooling Fan Motor

Front-C Heater

Fuse-M(Top)
Fuse-M(Middle)
Protection Fuse

Capacitor, R

ITEMS SPEC SPEC

2. CIRCUIT DIAGRAM

- 5 -

3-1. EXPLANATION OF FUNCTION

3-1-1. DISPLAY PART

(1) BEST MODEL(GR-J303TG)

(2) BETTER MODEL(GR-J303TS)

1. MICOM becomes "Lock" status in initial application of power, and the upper room is indicated as "Freezing Food." "Mid",
the middle room as "Cabbage" "Mid", and the lower room as "Cabbage" "Mid".

2. MICOM maintains the previous display status in power failure and re-application of power. But in case of a power-shut or
power reconnection during rhythm fermenting, the temperature returns to "Mid" for the applicable food type.

3. Buzzer sound neither ring ever pressing the button in "Lock" status, nor performs function.

3. MICOM FUNCTION AND EXPLANATIONS OF CIRCUITS

- 6 -

NOTCH

Temperature

setting

Cabbage/Radish/ Mul Kimchi

Vegetble/ Fruit Light Freezing Frozen Food Chilled Food

Min Mid Max Min Mid Max Min Mid Max Min Mid Max Max Min Mid Max

1.0°C -0.5°C -2.0°C 4.5°C 3.5°C 2.5°C -4.0°C -5.0°C -6.0°C -15°C -18°C -21°C -25°C 5.0°C 2.0°C 0.0°C

3-1-2. Food storage/seasoning function

(1) When selecting food type and storage temperature

1. Press the “Lock/Unlock” button for more than 2 seconds to “Unlock” the refrigerator.

2. When you press the “Uppper compartment”, ”Store” button in this condition, the storage temperature level changes from
“Mid” ’ ”Max” ’ ”Min” ’ ”Mid”, and the food type changes as follows when the storage temperature level changes from
“Min” ’ ”Mid”. (“Freeze” ’ ”Refrigerate” ’ ”Kimchi”)

3. When you press the “Middle compartment”, “Storage” button, the storage temperature level changes from “Mid” ’ ”Max”
’ ”Min” ’ ”Mid”, and the food type changes as follows when the storage temperature level changes from “Min” ’ ”Mid”.
(“Cabbage Kimchi” ’ ”Old Kimchi” ’ ”Light freezing” ’ ”Vegetable/fruit”)

4. When you press the “Lower compartment”, “Storage” button, the storage temperature level changes from “Mid” ’ ”Max”
’ ”Min” ’ ”Mid”, and the food type changes as follows when the storage temperature level changes from “Min” ’ ”Mid”.
(“Cabbage Kimchi” ’ ”Old Kimchi” ’ ”Broth Kimchi” ’ ”Vegetable/fruit”)

5. Press the “Lock/Unlock” button to end the food storage and storage temperature selection. At this time, if no button is
selected for 1 minute without the “Lock/Unlock” button pressed, the unit will automatically switch to the Lock condition and
end the selection.

(2) When selecting food type and rhythm fermenting (seasoning)

1. Press the “Lock/Unlock” button for more than 2 seconds to “Unlock” the refrigerator.

2. When you press the “Ferment” button at this condition, the rhythm fermenting (seasoning) changes from “Fermented 1(
)” ’ “Fermented 2 ( )” ’ ”More fermented ( )” ’ ”Underground fermented( )” ’ ”Less fermented 1( )” ’ ”Less
fermented 2( )”, and the food type changes from Middle compartment: “Cabbage Kimchi” ’ ”Old Kimchi” ’ ”Cabbage
Kimchi”, Lower compartment: “Cabbage Kimchi” ’ ”Radish Kimchi” ’ ”Broth Kimchi” ’ ”Cabbage Kimchi” when the
Rhythm Ferment (Seasoning) changes to “Less fermented 2” or “Fermented 1”. (But, the uppper compartment only has
the underground fermenting function.)

3. When you press the Ferment button when the food type is “Vegetable/fruit”, “Light freezing”, it is set to “Cabbage Kimchi
– Fermented 1”.

4. Press the “Lock/Unlock” button to end the food storage and storage temperature selection. At this time, if no button is
selected for 1 minute without the “Lock/Unlock” button pressed, the unit will automatically switch to the Lock condition and
end the selection.

(3) When selecting Flavor Keeping

1. Press the “Lock/Unlock” button for more than 2 seconds to “Unlock” the refrigerator.

2. The Flavor Keeping function can only be selected when the food type of “Cabbage Kimchi”, “Old Kimchi”, “Radish Kimchi”
or “Broth Kimchi” is selected.

3. When you press the “Flavor Keeping” button at this condition, the Flavor Keeping function will toggle between selected
and canceled. (But if both the middle compartment and the lower compartment has food type that can use Flavor
Keeping, operate in the order of Middle compartment Flavor Keeping ON ’ Lower compartment Flavor Keeping ON ’
Middle/Lower compartment Flavor Keeping ON ’ Middle/Lower compartment Flavor Keeping OFF ’ Middle
compartment Flavor Keeping ON.

4. Press the “Lock/Unlock” button to end the Flavor Keeping. At this time, if no button is selected for 1 minute without the
“Lock/Unlock” button pressed, the unit will automatically switch to the Lock condition and end the Flavor Keeping.

5. When you select the Flavor Keeping during the fermenting process, the fermenting will immediately end and the Flavor
Keeping function will start. AT this time, the storage temperature is automatically set to “Mid”.

6. When you select the Flavor Keeping, it controls at lower temperature to keep the current taste of Kimchi longer.
(-1 deg for “Min”, -0.5deg for “Mid” and 0 deg for “Max”.)

7. During the Flavor Keeping operation, the unit runs a cold shock operation every 12 hours.

8. When you select the rhythm fermenting while executing the Flavor Keeping, the Flavor Keeping function will be canceled.

- 7 -

- 8 -

3-1-3. Rhythm fermenting control pattern diagram

1. The fermenting control pattern varies, depending on the temperature of the Kimchi when it is placed into the storage, the
type of Kimchi being made and the degree of the seasoning selected.

2. In the 1st seasoning cycle, if the Kimchi is at room temperature, the cold control operates.

3. During the seasoning cycle, if the Kimchi is cold, the seasoning heater is turned on and if the Kimchi is warm, the
seasoning heater is turned off.

4. If a failure occurs, such as a sensor error during seasoning, the storage will default to Cabbage Kimchi storage status.

5. The 2ndseasoning is not included in the underground fermenting, in the 3rdseasoning, Perform the Low temperature
mature keeping the Temperature is 3

C

Time

Seasoning complete

Kimchi sensor temperature

18 ℃

(Mul Kimchi:

10 ℃)

5 ℃

1.0 ℃

-0.5 ℃

-2.0 ℃

Storage

operation

When the Kimchi placed in

the refrigerator is cool

When the Kimchi

placed in the refrigerator

is at room temperature

1st

seasoning

2nd

seasoning

3rd

seasoning

4th

seasoning

5th

seasoning

Seasoning start

: Seasoning heater
ON/OFF
: Seasoning heater
OFF

- 9 -

3-1-4. TEMPERATURE CONTROL AT UPPER, MIDDLE AND LOWER COMPARTMENT

(1) Temperature control at upper compartment

1. Turn COMP, upper compartment fan motor depending on temperature of the upper compartment sensor and cool them
by opening the 3-way valve to the upper compartment.

2. However, cooling of the upper compartment starts after cooling of the Middle/lower compartment is completed while the
middle/lower compartment is cooling (Max 25 min).

(2) Temperature control at middle/lower compartment

1.Turn COMP, middle compartment fan motor depending on temperature of the middle/lower compartment sensor and cool
them by opening the 3-way valve to the middle/lower compartment ,and opening the middle/lower damper.

2. However, cooling of the middle/lower compartment starts after cooling of the upper compartment is completed while the
upper compartment is cooling (Max 35 min).

(3) Operation conditions of COMP

1. COMP turns on by the upper compartment sensor and lower compartment sensor.

2. COMP turns off by the upper compartment sensor, middle compartment sensor and lower compartment sensor.

(4) Operation conditions of 3-way valve

1. Open the upper, middle and lower compartment valve by the upper, middle or lower compartment sensor .

2. Perform operation for minimum 25 minutes (for 35 minutes at middle, lower compartment) upon request of “open”
(unsatisfactory temperature) at the other side while COMP operates with the valve opened in one side, and then cutoff
the valve to other side. In this case, immediately cutoff the valve if temperature is met even if 25 minutes (35 minutes for
middle, lower compartment) have not passed.

3. In input of initial power, cool from the upper compartment where the upper compartment is Data Frz. (Deep Frz), Frz.
when all upper/middle/lower compartment is not satisfactory, and firstly cool from the middle, lower compartment for the
other case.

3-1-5. LCD BACK LIGHT CONTROL (LIMITED TO LCD MODEL)

1. To make the LCD display easy to see, the LCD back light is turned on for 1 minute for the initial power connection or for
20 seconds for the final button operation.

2. When you press any display button when the back light is turned off, the button command will not be executed nor the
buzzer sound generated. Only the back light will be turned on. But only the “Lock/Unlock” button will operate normally.
(When you press the button when the LCD back light is turned off, only the command to turn on the back light will be
executed.)

3. When you press the “Storage” button of the uppper compartment and the “Storage” button of the lower compartment
simultaneously for more than 1 second, the back light will be turned on and all the graphics on the LCD will be turned on.
When you release the buttons, the LCD graphics will return to the prior condition and the back light turned off.
(LCD graphic and back light ON/OFF check)

3-1-6. LOCK FUNCTION (DISPLAY BUTTON LOCK/UNLOCK)

1. The “Lock” LED is turned on in the Lock status in application of refrigerator power.

2. Turn the “Unlock” LED by pressing the Lock/Unlock button for 2 seconds or more to allow operation of the display button.

3. Buzzer sound neither rings ever by pressing any button other than the Lock/Unlock button, nor performs function with the
“Lock” LED turned on.

4. The “Lock” LED automatically turns on and becomes lock status unless operating the display button for more than a
minute with the “Unlock” LED turned on.

- 10 -

3-1-7. FRONT-C HEATER CONTROL

1. A heater for prevention of dewing is installed on the FRONT-C part between the middle compartment and the lower
compartment, and turns on at the time of COMP ON and for 20 minutes after COMP OFF.

2. It turns off in the test mode (turn on after power off for normal operation).

3-1-8. BUZZER RINGING

1. “Ding~Dong~” sound rings when pressing the front display button.

2. No buzzer rings if pressing the button not according to the operation order.

3-1-9. POWER FAILURE COMPENSATION FUNCTION

1. Previous operation is performs even applying power again after power failure. However, error status or test mode status
is excluded.

3-1-10. OPERATION RESPOND TO AMBIENT TEMPERATURE

1. This is function of maintaining keeping temperature constantly irrespective of season by compensating for the in­refrigerator temperature through ambient temperature of the refrigerator to prevent that the in-refrigerator temperature
changes according to ambient temperature (weak cold in winter, excess cold in summer).

3-1-11. DEFROSTING (REMOVAL OF FROST)

1. Defrosting is simultaneously performed by using the defrosting heater at the upper compartment and the middle
compartment whenever sum of compressor operation time reaches to 6 hours.

2. Defrosting is started if sum of compressor operation time reaches to 4 hours in input of initial power (or in returning from
power failure).

3. Complete defrosting function where defrosting sensor temperature of each room reaches to 7°C (16°C for GR-J213) for
the upper compartment, 16°C for the middle compartment respectively, after starting defrost work.
However, poor defrost is indicated if not reaching to 7°C (16°C for GR-J213) for the upper compartment, 16°C for the
middle compartment respectively 2 hours after starting defrost (See 3-1-11 Failure Diagnosis Function).

4. Poor defrost is indicated if the defrosting sensor is poor, and defrosting of the relevant room is not done.

-1.5 °C

-0.5 °C

4.0 °C

Keeping Temperature

(based on “Mid”)

Season Spring Summer Fall Winter

Operation Respond to Ambient Temperature

In General Operation

3-1-12. SEQUENTIAL OPERATION OF ELECTRICAL PARTS

Electrical parts such as COMP, defrosting heater at the upper & middle compartment, fan motor at the upper & middle
compartment, single motor damper and FRONT-C heater sequentially operate as followers for preventing noise and
damage of parts occurred by that various parts operate at the same time in input of initial power on and after test closing
(including temporary power failure, either):

- 11 -

Function Operation Sequence Remarks

In initial power on

When

defrosting

sensor

temperature at

the upper

compartment is

more than 45°C

(In purchasing,

movement)

When

defrosting

sensor

temperature at

the upper

compartment is

less than 45°C

(In power

failure, service)

No initial

operation is

done if error

occurs

during

operation.

POWER

ON

SINGLE
MOTOR

DAMPER

ON

COMP

ON

F-FAN

ON

SINGLE
MOTOR

DAMPER

OFF

5~6
sec

0.5

sec

3-WAY
VALVE

ON

3-WAY
VALVE

OFF

3~6
sec

0.5
sec

FRONT

-C

HEATER

ON

0.5
sec

0.3
sec

10

sec

0.3
sec

4~5
sec

STEPPING

MOTOR

DAMPER

ON

STEPPING

MOTOR

DAMPER

OFF

POWER

ON

DEFROSTING
HEATER
AT UPPER
COMPARTMENT

ON

DEFROSTING

HEATER
AT MIDDLE
COMPARTMENT

ON

DEFROSTING
HEATER
AT UPPER

COMPARTMENT

OFF

DEFROSTING
HEATER
AT MIDDLE

COMPARTMENT

OFF

FRONT

-C

HEATER

ON

FRONT

-C

HEATER

OFF

SINGLE
MOTOR

DAMPER

ON

COMP

ON

FRONT

-C

HEATER

ON

0.5

sec

0.3
sec

4

sec

0.3
sec

0.3
sec

4

sec

4

sec

0.3
sec

0.3
sec

10

sec

10~30

sec

UPPER

COMPARTMENT

FAN

ON

SINGLE
MOTOR

DAMPER

OFF

0.5

sec

5~6
sec

3-WAY
VALVE

ON

3-WAY

VALVE

OFF

0.5
sec

3~6
sec

STEPPING

MOTOR

DAMPER

ON

STEPPING

MOTOR

DAMPER

OFF

3-1-13. FAILURE DIAGNOSIS FUNCTION

(1) Failure Mode

1. Failure diagnosis function is intended in order that service is easily done when failure to affect performance of the product
during use occurs.

2. Function is neither done, nor buzzer sound rings even when pressing the button in occurrence of failure.

3. The product returns to normal operation if failure is released during display of failure code in occurrence of failure
(RESET).

4. LEDs other than failure code turn off in occurrence of failure.

Note 1) All LEDs except for failure display LED (F1, F2, F3, F4, F5) turn on if simultaneously pressing both upper “Store”

button and middle “Store” button for a second where poor ambient temperature sensor exists.

- 12 -

1

2

3

4

5

6

7

8

9

10

Failure Display

(Food LED)

F1 F2 F3 F4 F5

NO Item

Failures

Remarks

Failure of upper
compartment (K1)
sensor

Failure of middle
compartment (K2)
sensor

Failure of lower
compartment (K3)
sensor

Failure of upper
compartment
defrosting sensor

Failure of middle
compartment
defrosting sensor

sensor Failure of
ambient
temperature sensor

Failure of single
motor damper

Poor defrosting at
upper compartment

Poor defrosting at
middle compartment

Poor
communication

Upper compartment sensor is disconnected
or shorted

Middle compartment sensor is
disconnected or shorted

Lower compartment sensor is disconnected
or shorted

Upper compartment defrosting sensor is
disconnected or shorted

Middle compartment defrosting sensor is
disconnected or shorted

Ambient temperature sensor is
disconnected or shorted

When ON/OFF of the reed-S/W is not
dectected even when driving the single
motor damper for 2 minutes

When defrosting sensor at the upper compartment
does not reach to more than 7°C even when two
hours have passed after starting defrost

When defrost sensor at the middle compartment
does not reach to more than 16°C even when
two hours have passed after starting defrost

When no communication is consecutively
done for 30 seconds

* Check wiring of respective

relevant sensor.

Damper motor damaged,
frozen, coil damaged, driving
IC(photo coupler) failure

Short of temperature fuse,
short of heater, clogging of
drain, poor heater driving relay

Short of temperature fuse,
short of heater, clogging of
drain, poor heater driving relay

Taking out of connector, Poor
TR on communication part

FS

US

LS

d1

d2

Note 1)

dP

H1

H2

CO

BEST MODEL
(GR-J303TG)

BETTER MODEL
(GR-J303TS)

(2) Load Operation in Failure

- 13 -

Classification

ITEM

NO

UPPER

COMPARTMENT

FAN

COMP

DEFROSTING

HEATER OF

UPPER

COMPARTMENT

DEFROSTING

HEATER OF

MIDDLE

COMPARTMENT

STEPPING

MOTOR

DAMPER

SINGLE
MOTOR

DAMPER

3-WAY
VALVE

FRONT-C

HEATER

MIDDLE

COMPARTMENT

FAN

Normal
Failure of

Upper
compartment
(K1) sensor

Failure of
Middle
compartment
(K1) sensor

Failure of
Upper
compartment
(K1) sensor

Failure of
Upper
compartment
defrosting
sensor

Failure of
Middle
compartment
defrosting
sensor

Failure of
ambient
Temperature
sensor

Poor
defrosting
at upper
compartment

Poor
defrosting
at middle
compartment

Failure of
single
motor
damper

Poor
communication

1

2

3

4

5

6

7

8

9

10

11

O

15 min

ON/

15 min

OFF

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

O

Don’t

defrost

(immediat

ely return)

O

O

O

O

O

O

O

O

O

O

O

Don’t

defrost

(immediat

ely return)

O

O

O

O

O

O

O

15 min
OPEN/
15 min

CLOSE

O

O

O

(No

compensation
of ambient
temperature

)

O

O

O

O

O

O

O

10 min
OPEN/
15 min

CLOSE

O

O

(No
compensation
of ambient
temperature

)

O

O

Perform

normal
initialization
by checking

operation

in the cycle

of 1 hour

O

O

O

(Linked

with

COMP.

However,

FRONT-C

heater

turns off

for 15
minutes
and turn

on again if
the heater

turn on

time

continues

for more

than 40

minutes)

3-1-14. TEST FUNCTION

1. Test function is intended to check function of PCB and the product and find a failure part with failure status.

2. The test S/W exists on the main PCB, and ends the test mode after 2 hours irrespective of the test mode, and then
returns to normal status.

3. Function button is neither detected, nor button recognition sound comes out during the test mode.

4. Ensure to take the power cords out in completion of the test mode so that normal status will be arrived.

5. Release the test mode and display the failure mode if failure such as sensor failure during the test mode.

6. No test mode is performed even when pressing the test button during display of failure code.

• LED check function

All LEDs turn on if pressing both upper “Store” button and middle “Store” button at the same time for 1 second or more,
and display the previous status if releasing the button.

• FRONT-C Heater touching inspection mode

The FRONT-C heater consecutively turns on for 5 minutes and is then released if pressing both upper “Store” button and
lower “Ferment” button for 5 seconds or more. It is released if pressing them again for 5 senconds or more.

- Release check: LED on the remainder time display part of the lower compartment turns on with pressing for 5 seconds or
more.

- Input check: LED on the flavor keeping part turns on with pressing for 5 seconds or more.

- 14 -

MODE OPERATION DETAILS REMARKS

TEST1

TEST2

Normal

status

Press the test S/W
once

Press the test S/W
once in the test mode 1

Press the test S/W 3
times in the test mode 2

1. COMP (* Fan motor at machine room) ON

2. Defrost heater OFF at upper, middle compartment.

3. FRONT-C heater OFF

4. Fan motor at upper/middle compartment, damper
at middle/lower compartment and 3-way valve
operates to cool the upper/middle&lower
compartment in interval of 16/24 minute.

5. For display, the only “Min” LED of the upper room
turns on.

1. COMP (* Fan motor at machine room) OFF

2. Fan motor OFF at upper, middle compartment

3. Defrost heater ON at upper, middle compartment

4. FRONT-C heater ON

5. All dampers at middle, lower compartment are
closed.

6. 3-way valve maintains previous status.

7. For display, the only “MIN” LED of the upper room
turns on.

Returns to initial status

Returns to normal status
when maximum 2 hours
have passed.

Defrost sensor at the
upper compartment
performs initialization at
more than 7 °C, and
middle defrost sensor at
more than 16 °C (COMP
delay for 7 minutes)

COMP operates after
delay for 7 minutes