LG LRFC25750xx Service Manual

CAUTION

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

REFRIGERATOR

SERVICE MANUAL

TITANIUM

http://biz.lgservice.com

MODEL:LRFC25750ST

LRFC21755SB

LRFC21755ST

STAINLESS-STEEL

LRFC21755TT

CONTENTS

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

SPECIFICATIONS................................................................................................................................................................... 3

PARTS IDENTIFICATION ....................................................................................................................................................... 4

DISASSEMBLY.................................................................................................................................................................... 5-6

DOOR................................................................................................................................................................................... 5

FAN AND FAN MOTOR........................................................................................................................................................ 6

DEFROST CONTROL ASSEMBLY...................................................................................................................................... 6

LAMP.................................................................................................................................................................................... 6

CONTROL BOX-REFRIGERATOR ...................................................................................................................................... 6

MULTI DUCT ........................................................................................................................................................................ 6

ADJUSTMENT..................................................................................................................................................................... 7-8

COMPRESSOR.................................................................................................................................................................... 7

PTC-STARTER ..................................................................................................................................................................... 7

OLP (OVERLOAD PROTECTOR)........................................................................................................................................ 8

TO REMOVE THE COVER PTC...........................................................................................................................................8

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

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

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

PTC AND OLP.................................................................................................................................................................... 11

OTHER ELECTRICAL COMPONENTS ............................................................................................................................. 12

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

REFRIGERATION CYCLE ............................................................................................................................................ 14-15

OPERATION PRINCIPLE & REPAIR METHOD OF ICEMAKER .................................................................................. 16-19

DESCRIPTION OF FUNCTION & CIRCUIT OF MICOM ............................................................................................... 20-38

EXPLODED VIEW & REPLACEMENT PARTS LIST ......................................................................................................... 39-

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 onto electric elements or the machine parts.

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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. Service on the refrigerator should be performed by a qualified technician. Sealed system repair must be performed by a CFC certified technician.

1. SPECIFICATIONS

21 cu. ft. / 25 cu. ft.

ITEMS SPECIFICATIONS

DOOR DESIGN Side Rounded

DIMENSIONS (inches)

NET WEIGHT (pounds)

COOLING SYSTEM Fan Cooling

TEMPERATURE CONTROL Micom Control

DEFROSTING SYSTEM

DOOR FINISH Embossed Metal, VCM, Stainless

HANDLE TYPE Bar

INNER CASE ABS Resin

INSULATION Polyurethane Foam

35 3/4 X 30

35 3/4

278 (

302 (

Full Automatic

Heater Defrost

X 69

X 34

21cu.ft)

25cu.ft)

/4 (WX

X 69

(WXDXH) 25cu.ft

DXH) 21cu.ft

ITEMS SPECIFICATIONS

VEGETABLE TRAY Opaque Drawer Type

COMPRESSOR PTC Starting Type

EVAPORATOR Fin Tube Type

CONDENSER Wire Condenser

REFRIGERANT R-134a (115 g)

LUBRICATING OIL Freol @ 10G (310 cc)

DEFROSTING DEVICE SHEATH HEATER

REFRIGERATOR 60 W (2EA)

LAMP

FREEZER 40 W (1EA)

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2. PARTS IDENTIFICATION

Digital Sensor

Control

Refrigerator Light

Shelves

Optibin Crisper

Keeps fruits and

vegetable fresh

and crisp

Customcube

Icemaker

Glide N Serve

Ice Bin

Durabase

Divider

Pull out Drawer

Freezer Door Rack (Tilting)

Design-A-Door

Wine Holder

Dairy Bin

Egg Box

Design-A-Door

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3. DISASSEMBLY

HINGE

HINGE COVER

GASKET

LOWER HINGE

BOLT

3-1 DOOR

● Refrigerator Door

1. Remove the hinge cover by pulling it upwards.

2. Loosen the hex head bolts attaching the upper hinge to the body and lift the freezer door.

Figure 1

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

● Freezer Door

1. Loosen the hex head bolts attaching the lower hinge to the body to remove the refrigerator door only.

Figure 3

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

Figure 2

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3-2 FAN AND FAN MOTOR

BRACKET

MOTOR

GRILLE

FAN MOTOR

FAN

GRILLE ASSEMBLY

DEFROST-CONTROL ASSEMBLY

CONTROL BOX

COVER LAMP

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.

Figure 5

3-4-1 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. 60 W2EA).

Figure 9

3-4-2 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.

3-3 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)

3-4 LAMP

Figure 6

Figure 7

3-5 CONTROL BOX-REFRIGERATOR

1. First, remove all shelves in the refrigerator, than remove the Refrigerator control Box by loosening 2 screws.

Figure 10

2. Remove the Refrigerator Control Box by pulling it downward.

3. Disconnect the lead wire on the right position and separate the lamp sockets.

3-6 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.

Figure 8

Figure 11

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4. ADJUSTMENT

PTC STARTER

SEALED

TERMINAL

COMPRESSOR MOTOR

PTC

OVERLOAD PROTECTOR

Resistance Starter Capacitor Running

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 BaTiO

(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

Figure 12

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.

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4-3 OLP (OVERLOAD PROTECTOR)

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)

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

1) Remove the Cover Back M/C.

(2) Remove the screw on Cover PTC.

Figure 13

(3) Remove two Housings on upper part of Cover PTC.

(4) Take out the cover PTC from upper to lower position

like .

(5) Turn 45° in the direction of  and take it out.

(6) Assembly in reverse order of disassembly.

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5. CIRCUIT DIAGRAM

BETTER MODEL

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6. TROUBLESHOOTING

YES

The range of resistance is between 1~50Ω(ok)

Open or short

YES

6-1 COMPRESSOR AND ELECTRIC COMPONENTS

Power Source.

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

No Voltage.

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

(Rated Voltage ±10%)?

OLP disconnected?

Advise customer that power supply needs to be checked by an electrician.

Replace OLP.

Check connection condition.

Reconnect.

Check resistance of Motor Compressor.

Check resistance of PTC-Starter.

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

Check resistance of two terminals in PTC-Starter.

Replace Compressor.

Reference Page12.

Check OLP.

Check resistance of two terminals in OLP.

Reference Page12.

Check starting state.

Check the power supply under load. (Compressor attempting to re-start after being off for 5 minutes).

Supply voltage rating with ±10%.

Did compressor start?

Compressor is OK

Replace the compressor

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6-2 PTC AND OLP

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 : 6.8Ω±30%

The resistance value is 0Ω (short) or ∞ (open).

Check another electric component.

Replace OLP.

Replace PTCStarter.

Figure 14

Figure 15

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6-3 OTHER ELECTRICAL COMPONENTS

▼ Not cooling at all

Compressor doesn't run.

▼ Poor cooling performance

Compressor runs poorly.

Check for open short or incorrect resistance readings in the following components

a. Starting devices

b. OLP

c. Compressor coil

d. Wiring harness

Check starting voltage.

Check voltage at starting devices.

Cause

Short, open, or broken.

Poor contact or shorted.

Coil open or shorted.

Poor contact or shorted.

Low voltage.

Poor or broken or open contact.

Replace indicated component.

Advise customer that the Power supply needs to be checked by an electrician.

Replace indicated component.

Fan motor doesn't run.

Heavy frost buildup on EVAPORATOR.

Check current flowing in sub-coil of Compressor.

Check rating of OLP.

Check wiring circuit.

Check Fan Motor.

Check current flow in the following components: Sensor Fuse-M

Check current flow in the Defrost Heater.

Shorted.

Lack of capacity.

Wire is open or shorted.

Coil is shorted or open.

Open.

Replace indicated component.

Replace Defrost Heater.

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6-4 SERVICE DIAGNOSIS CHART

COMPLAINT POINTS TO BE CHECKED REMEDY

No Cooling.

Cools poorly.

Food in the Refrigerator is frozen.

Condensation or ice forms inside the unit.

Condensation forms in the Exterior Case.

There is abnormal noise.

• 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.

• 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.

Door does not close well.

Ice and foods smell unpleasant.

● Other possible problems:

Check if frost forms in the freezer.

Check the refrigeration system.

Check the Thermistor.

• 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.

Not defrosting

The system is faulty.

The operation of the Thermistor is incorrect.

• 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.

Check Components of the defrosting circuit.

Perform sealed system repair.

Replace the Thermistor.

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6-5 REFRIGERATION CYCLE

▼ Troubleshooting Chart

CAUSE

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.

LEAKAGE

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

CLOGGED BY DUST

PARTIAL Freezer Flowing sound of refrigerant A little higher • Normal discharging of the CLOG compartment and is heard and frost forms than ambient • refrigerant.

WHOLE CLOG

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

COMPRESSION

COMP- Freezer and Low flowing sound of A little higher • Low pressure at high side

DEFECTIVE

RESSION Refrigerator refrigerant is heard and than ambient • of compressor due to low

STATE OF

THE UNIT

Refrigerator don't frost forms in inlet only. temperature. • Normal cooling is possible by cool normally. • restoring the normal amount of

Refrigerator don't formed. • restoring the normal amount of cool normally. • refrigerant and repairing the leak.

Refrigerator don't in inlet only. temperature. • The capillary tube is faulty. cool normally.

Freezer compartment and Refrigerator don't cool.

don't cool. frost forms in inlet only. temperature. • refrigerant level.

STATE OF THE

EVAPORATOR

Flowing sound of refrigerant Equal to ambient • Normal discharging of the is not heard and frost isn't temperature. • Refrigerant. formed.

TEMPERATURE

OF THE

REMARKS

COMPRESSOR

• refrigerant and repairing the leak.

temperature. • capillary tube.

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.

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