LG LRTBC1825xx Service Manual

CAUTION

BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

REFRIGERATOR

SERVICE MANUAL

http://biz.lgservice.com

MODEL : LRTBC1825T LRTBC2025T

COLOR: TITANIUM

SAFETY PRECAUTIONS....................................................................................................................................................... 2

SERVICING PRECAUTIONS.................................................................................................................................................. 3

SPECIFICATIONS................................................................................................................................................................... 4

PARTS IDENTIFICATION....................................................................................................................................................... 5

DISASSEMBLY.................................................................................................................................................................... 6-7

DOOR................................................................................................................................................................................... 6

DOOR SWITCH.................................................................................................................................................................... 6

THERMOSTAT..................................................................................................................................................................... 6

FAN AND FAN MOTOR........................................................................................................................................................ 7

DEFROST CONTROL ASSEMBLY...................................................................................................................................... 7

LAMP.................................................................................................................................................................................... 7

CONTROL BOX-R................................................................................................................................................................ 7

ADJUSTMENT........................................................................................................................................................................ 8

COMPRESSOR.................................................................................................................................................................... 8

POSITIVE TEMPERATURE COEFFICIENT-STARTER....................................................................................................... 8

OVERLOAD PROTECTOR.................................................................................................................................................. 9

CIRCUIT DIAGRAM................................................................................................................................................................ 9

TROUBLESHOOTING..................................................................................................................................................... 10-15

COMPRESSOR AND ELECTRIC COMPONENTS ........................................................................................................... 10

POSITIVE TEMPERATURE COEFFICIENT AND OVERLOAD PROTECTOR................................................................. 11

DEFROST TIMER .............................................................................................................................................................. 11

OTHER ELECTRIC COMPONENTS ................................................................................................................................. 12

SERVICE DIAGNOSIS CHART.......................................................................................................................................... 13

REFRIGERATING CYCLE............................................................................................................................................ 14-15

OPERATION PRINCIPLE AND REPAIR METHOD OF ICE MAKER ............................................................................ 16-27

EXPLODED VIEW .......................................................................................................................................................... 28-31

REPLACEMENT PARTS LIST............................................................................................................................................ 32-

CONTENTS

- 2 -

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. If you use any kind of appliance, check regular current, voltage, and capacity.

5. Don't touch metal products in the freezer with wet hands. This may cause frostbite.

6. Prevent water from following onto electric elements in the mechanical parts.

7. Close the top door before opening the bottom door. Otherwise, you might hit your head when you stand up.

8. When tilting the refrigerator, remove any materials on the refrigerator, especially the thin plates (ex. Glass shelf or books.)

9. When servicing the evaporator, wear cotton gloves. This is to prevent injuries from the sharp evaporator fins.

10. Leave the disassembly of the refrigerating cycle to a specialized service center. The gas inside the circuit may pollute the environment.

SAFETY PRECAUTIONS

AIR RECHARGING IN COMPRESSOR

Test the refrigeration system connecting it electrically before refilling operation. It is necessary to ascertain the function of the motor-compressor and identify the defects immediately. If defects have been found, empty the old system of possible R-134a residue by breaking off the end of the extension piece at its narrow point. (Figure 1)

Replace the filter and any damaged components. Unsolder and pull off the piece remaining inside the service tube and then attach an complete extension with male Hansen and at last, solder it to the same tube again. (Figure 2)

It is necessary to execute the soldering operation with valve open so that the fumes caused by oil residue can come out freely without blowholes between two tubes during the heating the of the point to be soldered.

The extension fitted with the male Hansen is connected to the female fitting of the vacuum pump tube. (Figure 3)

Air evacuating from the system begins as soon as the pump starts. The refrigeration system must be kept under vacuum until the reading on the low-pressure gauge indicates vacuum (0 absolute, -1 atm., -760 mm hg). In any case it is advisable to keep the pump running for about 30 minutes. (Figure 3)

If considerable leakage occurs, it will be necessary to stop the vacuum pump and to add a small quantity of Freon to the system. If vacuum should not be obtained (pressure gauge can't fall to 1 atmosphere), start the refrigeration unit and find the leakage with special leak-finder. When the defective soldering point is visible, repair it after opening the extension tube valve and reestablishing the normal outside pressure inside the group.

Because the melted alloy is sucked into the tubes and blocks them, the pressure must be rebalanced when vacuum is in the system when soldering. As soon as the

vacuum operation is over, add the quantity in grams of R-134a to the refrigeration system. Remember that every system has an exact quantity of R-134a that can be added with a tolerance of ±5 grams. (Figure 4)

Before performing this operation (if the vacuum pump and refilling cylinder are connected), make sure that the valve placed between the vacuum pump and the refilling tube is closed in order to keep the Freon for addition to the system. (Figure 5)

In addition, check the graduated scale on the cylinder for the quantity of R-134a to be added, for example, if we have 750 grams of Freon in the cylinder and must add 140 grams to the group, this amount will be reached when R-134a has dropped to 610 grams, remembering that the indicator shows a lower limit of meniscus. Do this after choosing the scale corresponding to the gas pressure different scales reported as the same gas pressure indicated by the pressure gauge on the top of the column.

To make R-134a flow into the system, open the valve placed at the base of the cylinder connected to the filling tube. The amount of Freon cannot be added to the system all at once because it may cause a blocking of motorcompressor. Therefore, proceed by adding the original quantity of about 20-30 grams and close the valve immediately.

The pressure rises and the motor compressor must start sucking the gas and lowering the pressure again. Open the valve again, maintaining the same manner until reaching to the quantity of R-134a established for the system being charged. When the system is running, the suction pressure must be stabilized between 0.30 to 0.6 (0.10 to 0.4) atmosphere.

SERVICING PRECAUTIONS

- 3 -

POINT TO BE BROKEN

SERVICE TUBE EXTENSION

CHARGE TUBE EXTENSION

FEMALE HANSEN

MALE HANSEN

SOLDERING POINT

Figure 1 Figure 2

TO THE VACUUM PUMP

PRESSURE GAUGE

Figure 3

TO THE R-134a CYLINDER

TO THE REFRIGERATION SYSTEM

Figure 4

FILLING OR CHARGE TUBE

VALVE TO BE OPENED WHEN REFILLING

VALVE TO BE CLOSED AFTER VACUUM

TO THE CHARGE CYLINDER

TO THE REFRIGERATION SYSTEM

TO THE VACUUM PUMP

Figure 5

1. SPECIFICATIONS

- 4 -

ITEMS SPECIFICATIONS

DOOR DESIGN All Rounded DIMENSIONS (mm)

754.5 X 735 X 1732 (W X D X H

) NET WEIGHT (kg) 90 COOLING SYSTEM Fan Cooling TEMPERATURE CONTROL Knob Dial

Full Automatic

DEFROSTING SYSTEM Heater Defrost

With a Timer DOOR FINISH Vinyl Coated Metal HANDLE TYPE Bar INNER CASE ABS Resin INSULATION Polyurethane Foam

ITEMS SPECIFICATIONS

VEGETABLE TRAY Transparent Drawer Type COMPRESSOR PTC Starting Type EVAPORATOR Fin Tube Type CONDENSER Wire Condenser REFRIGERANT R-134a (155 g) LUBRICATING OIL ISO10 (280 cc) DEFROSTING DEVICE SHEATH HEATER

FREEZER 25 W

LAMP

REFRIGERATOR 40 W

1. Ref. No.: LRTBC1825T

ITEMS SPECIFICATIONS

DOOR DESIGN All Rounded DIMENSIONS (mm)

754.5 X 788 X 1732 (W X D X H

) NET WEIGHT (kg) 93 COOLING SYSTEM Fan Cooling TEMPERATURE CONTROL Knob Dial

Full Automatic

DEFROSTING SYSTEM Heater Defrost

With a Timer DOOR FINISH Vinyl Coated Metal HANDLE TYPE Bar INNER CASE ABS Resin INSULATION Polyurethane Foam

ITEMS SPECIFICATIONS

FREEZER 25 W

LAMP

REFRIGERATOR 40 W

2. Ref. No.: LRTBC2025T

2. PARTS IDENTIFICATION

- 5 -

Automatic Ice Maker

Ice Cube Box

FREEZER

COMPARTMENT

REFRIGERATOR

COMPARTMENT

Freezer Temperature

Control Dial

Freezer Shelf

Door Cooling

On the refrigerator door, the cold air passageway is installed to supply cold air to the doorside of the refrigerator compartment.

Temperature

Control Dial

Lamp

Shelves

Egg Box

(option)

Snack Corner

Crisper

Used to keep fruits

and vegetables fresh and crisp.

Freezer Door Bin

Lamp

Refrigerator Door Rack

Can Server

Adjustable Door Bin

Leveling Screw (Inside)

Dairy Corner

Base Grille

1. Bend down.

2. Push the grille toward the refrigerator.

3. <Three protecting

parts> should be beneath

the bottom plate while

pushing the grille.

3-1 DOOR

● Freezer Door

1. Remove the hinge cover by pulling it upwards.

2. Loosen hexagonal bolts fixing the upper hinge to the body and lift the freezer door.

3. Pull out the door gasket to remove from the door foam assembly.

● Refrigerator Door

1. Loosen 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, pull out it with a slotted type driver as shown in (figure 9).

2. Disconnect the lead wire from the switch.

3-3 THERMOSTAT

1. Remove Control Box-R by loosening 2 screws attached to ceiling of Refrigerator compartment (Figure 10)

2. Separate the thermostat and dial knob F.

3. Remove the thermostat by disconnecting the lead wire.

3. DISASSEMBLY

- 6 -

BOLT

HINGE

HINGE COVER

Figure 6

GASKET

Figure 7

LOWER HINGE

BOLT

Figure 8

DOOR SWITCH

LEAD WIRE

Figure 9

Figure 10

3-4 FAN AND FAN MOTOR

1. Remove the freezer shelf. (If your refrigerator have an Ice Maker, disassemble the Ice maker first)

2. Remove the grille by pulling it out and by loosening a screw.

3. Remove the Fan Motor assembly by loosening 4 screws and disassemble the shroud.

4. Pull out the fan and separate the Fan Motor and Bracket.

3-5 DEFROST CONTROL ASSEMBLY

Defrost control assembly consists of Defrost Thermostat and FUSE–M.

Defrost Thermostat functions to defrost automatically and it is attached to metal side of the Evaporator and senses Temp.

Fuse-M is a safety device for preventing over-heating of the Heater when defrosting.

At the temperature of 77°C, it stops the emission of heat from the Heater.

1. Pull out the grille assembly.

2. Separate the connector connected with the Defrost Control assembly and replace the Defrost Control assembly after cutting the Tie Wrap. (Figure 14)

3-6 LAMP

3-6-1 Refrigerator room 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 original. (Max 40 W)

3-6-2 Freezer room lamp

1. Unplug refrigerator or disconnect power.

2. Reach behind light shield to remove bulb.

3. Replace bulb with a 25-watt appliance bulb.

4. Plug in refrigerator or reconnect power.

3-7 CONTROL BOX-R

1. First, remove all shelves in the refrigerator and Control Box-R by loosening 2 screws.

2. Remove the Control Box-R by pulling it downward.

3. Disconnect the lead wire on the right position and seperate timer, themostat, Lamp socket, etc.

- 7 -

FAN

BRACKET

SHROUD

GRILLE

FAN MOTOR

Figure 12

SHROUD-F

Figure 13

DEF-THERMO

FUSE-M

HOLDER FUSE

Figure 14

REFRIGERATOR ROOM LAMP

Figure 16-1

Figure 16-2

CONTROL BOX

COVER LAMP

Figure 17

FREEZER ROOM LAMP

4-1 COMPRESSOR

4-1-1 Role

The compressor intakes low temperature and low pressure gas evaporated from evaporator of the refrigerator, and condenses this gas to high temperature and high pressure gas, and then plays delivering role to condenser.

4-1-2 Composition

The compressor includes overload protection. The PTC starter and OLP (overload protector) are outside the compressor. Since the compressor is manufactured to tolerances of 1 micron, and is 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) No Strike

If applying forcible power or strike (dropping or careless handling), poor operation and noise may occur.

(3) Use proper electric components appropriate to the

Compressor.

(4) Note to Keep Compressor.

If Compressor gets wet in the rain and rust in the pin of Hermetic Terminal, the result may be poor operation and poor contact may cause.

(5) Be careful that dust, humidity, and welding flux don't

contaminate the compressor inside when replacing the Compressor. Dust, humidity, and flux due to welding which contaminates the cylinder may cause lockage and noise.

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 BaTiO

(2) The higher the temperature is, the higher the resistance

value. These features are used as starting device for the Motor.

4-2-2 Role of PTC-Starter

(1) PTC is attached to Hermetic Compressor used for

Refrigerator, Show Case, and starting Motor.

(2) Compressor for household refrigerator applies to

single-phase induction Motor. For normal operation of the single-phase induction

motor, in the starting operation flows in both main coil and sub-coil. After the starting is over, the current in subcoil is cut off. The proper features of PTC play all the above roles. So, PTC is used as a motor starting device.

4-2-3 PTC-Applied Circuit Diagram

● According to Starting Method for the Motor

4-2-4 Motor Restarting and PTC Cooling

(1) For restarting after power off during normal

Compressor Motor operation, plug the power cord after 5 min. for pressure balance of Refrigerating Cycle and PTC cooling.

(2) During normal operation of the Compressor Motor, PTC

elements generate heat continuously. Therefore, if PTC isn't cooled for a while after the power has been shut off, the motor will not restart.

4-2-5 Relation of PTC-Starter and OLP

(1) If the power is off during operation of Compressor and

the power is on before the PTC is cooled, (instant shutoff within 2 min. or unplugging and reconnecting), the PTC isn't cooled and a resistance value grows. As a result, current can't flow to the sub-coil, the Motor can't operate, and the OLP operates by flowing over current in only in the main-coil.

(2) While the OLP repeats on and off operation about 3-5

times, PTC is cooled and Compressor Motor performs normal operation.

If OLP doesn't operate when PTC is not cooled, Compressor Motor is worn away and causes circuitshort and fire. Therefore, always use a properly attached OLP.

4-2-6 Note to Use PTC-Starter

(1) Be careful not to allow over-voltage and over-current. (2) Do not strike

Don't apply a forcible power or strike.

(3) Keep apart from any liquid.

If liquid, such as oil or water away enters the PTC, PTC materials may fail due to insulation breakdown of the material itself.

(4) Don't change PTC at your convenience.

Don't disassemble PTC and case. If the exterior to the PTC-starter is damaged, resistance value is altered and it may cause poor starting of the compressor motor may cause.

(5) Use a properly attached PTC.

4. ADJUSTMENT

- 8 -

PTC STARTER

HERMETIC TERMINAL

COMPRESSOR MOTOR

PTC

OVERLOAD PROTECTOR(O.L.P)

RSIR

Figure 19

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 cutting the current to the Motor if the temperature rises and activates the bimetal spring in the OLP.

(2) When over-voltage flows to Compressor motor, the

Bimetal works by heating the heater inside the OLP, and the OLP protects Motor by cutting off current which flows to the Compressor Motor.

4-3-2 Role of the OLP

(1) The OLP is attached to the Hermetic Compressor used

for the Refrigerator and prevents the Motor Coil from being started in the Compressor.

(2) Do not turn the Adjust Screw of the OLP in any way for

normal operation of the OLP. (Composition and connection diagram of OLP)

- 9 -

5. CIRCUIT DIAGRAM

CONTACTING POINT

COVER

BIMETAL

CONTACTING POINT

HEATER

TERMINALS

ADJUST SCREW

HEATER

BIMETAL

Figure 21

Ref. No.: LRTBC1825T Ref. No.: LRTBC2025T

6. TROUBLESHOOTING

- 10 -

6-1 COMPRESSOR AND ELECTRIC COMPONENTS

4 5

YES

Power Source.

No Voltage.

(Rating Voltage ±10%)?

Replace OLP.

Reconnect.

Replace PTC-Starter.

Replace OLP.

O.K.

Check connection condition.

OLP disconnected?

Advise the customer to use a regular transformer.

Replace Compressor.

OLP works within 30 sec. in forcible OLP operation by turning instant power on and off.

Components start in the voltage of Rating Voltage ±10% below.

Applied voltage isn't in the range of Rating Voltage ±10%.

Remove the PTCStarter from the Compressor and measure the voltage between Terminal C of Compressor and Terminals 5 or 6 of PTC.

Check the resistance among M-C, S-C and M-S in Motor Compressor.

Check the resistance of two terminals in PTC-Starter.

Check if applying a regular OLP.

Measure minimum starting voltage after 5 min. for balancing cycle pressure and cooling the PTC.

Check the resistance of Motor Compressor.

Check the resistance of PTC-Starter.

Check OLP.

Check starting state.

- 11 -

6-2 PTC AND OLP

YES

Cam Shaft

Normal operation of Compressor is impossible or poor.

Separate the PTCStarter from Compressor and measure the resistance between No. 5 and 6 of PTCStarter with a Tester or Wheatstone Bridge. (Figure 21)

Separate the OLP from Compressor and check the resistance value between two terminals of OLP with a Tester. (Figure 22)

Observation value is 220V/50Hz : 22Ω±30% 115V/60Hz : 6.8Ω±30% 240V/50Hz : 33Ω±30% 127, 220V/60Hz : 22Ω ±30%

The resistance value is 0 or several hundred Ω.

The value is ∞.

Check another electric components.

Replace OLP.

Check another electric components.

Replace PTCStarter

Figure 21

Figure 22

Figure 23

Normal operation of the Defrost Timer is impossible.

No defrosting.

Poor cooling.

Position the Cam Shaft to the point of first click sound and check the current flowing between terminals No. 1(brown) and No. 2(bright orange). Next, position the Cam Shaft to the point of second click sound and check the current flowing between terminals No. 1 (brown) and No. 4 (black) (Figure 23).

Turn the Cam Shaft.

Shake about 3 times with holding the Cam Shaft and Body softly.

The resistance is ∞.

The resistance is 0Ω or variable.

The resistance is about 220V/50Hz : 20KΩ 115V/60Hz : 7.8KΩ

Loud click sound.

Replace the Defrost Timer.

Check the another electric components.

Replace the Defrost Timer.

6-3 DEFROST TIMER

- 12 -

▼ Cooling is impossible

Compressor doesn't run.

Compressor runs poorly.

Check a starting voltage.

Check if current flows to the following components.

a. Thermostat b. Starting devices

c. OLP d. Compressor coil

e. Defrost Timer f. Circuit parts

Low voltage.

Poor contacting and gas leakage.

Shorted or broken. Poor contacting

or shorted. Coil shorted.

Poor contacting or shorted.

Poor contacting and broken.

Shorted.

Lack of capacity.

Coil of motor Compressor.

Replace the compressor.

Replace indicated component.

Raise the voltage.

Replace indicated component.

Cause

Check if current flows to starting devices.

Check current flowing in sub-coil of Compressor.

Check capacity of OLP.

The items described above are normal.

▼ Cooling ability is poor

Fan motor doesn't run.

Much frost is built upon the EVAPORATOR.

Poor contacting.

Coil is shorted.

Shorted.

Replace indicated component.

Running is poor. (Coil is shorted.)

Check current flowing of the door S/W.

Check current flowing in the Fan Motor.

Check the running condition of Timer.

Check current flowing of the following components.

• Defrost Thermostat

• Fuse-M

Check current flowing of the following components.

• L-cord

• TE-Plate Heater

6-4 OTHER ELECTRIC COMPONENTS

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