LG LFC20760SW Service Manual
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LG LFC20760SW Service Manual

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REFRIGERATOR
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
MODELS:
LFC20760SW /04
LFC20760SB /04
LFC20760ST /04

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Summary of Contents for LG LFC20760SW

  • Page 1 REFRIGERATOR SERVICE MANUAL CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. MODELS: LFC20760SW /04 LFC20760SB /04 LFC20760ST /04...
  • Page 2 ECN (Engineering Change Number) Rev.01 SVC Improvement opening door freezer (change design of rails) Rev.02 Change Cover Lower, Case PCB and Rail Rev.03 Change compressor & base compressor Rev.04 Valve inclined in order to improve water house connection...

  • Page 3: Table Of Contents

    CONTENTS SAFETY PRECAUTIONS ........................1. SPECIFICATIONS ......................... 2. PARTS IDENTIFICATION ......................3. DISASSEMBLY ..........................3.1 Remove Refrigerator Door ....................... 3.2 Replace Refrigerator Door......................3.3 Remove Door Handle........................ 3.4 Door Gasket Removal....................... 3.5 Door Gasker Replacement......................3.6 Door Alignment.......................... 3.7 Pull Out Drawer......................... 3.8 Fan and fan motor ........................

  • Page 4: Specifications

    1. SPECIFICATIONS LFC20760SW LFC20760SB LFC20760ST SPECIFICATIONS Super White Black Stainless Color 29.8 (W) x 32.2 (D) x 68.4 (H) in Dimensions Net Weight 111 Kg Capacity 20 cuft Refrigerant R134a Climate class Temperatel (T) Rated Rating 115V~ / 60Hz Cooling System...

  • Page 5: Parts Identification

    2. PARTS IDENTIFICATION 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. Filter (Inside)* Digital Sensor Control Dairy Bin...

  • Page 6: Disassembly

    3. DISASSEMBLY 3-1 REMOVING REFRIGERATOR DOOR Left Door Left Door Loosen the cover screw (1). Lower the door onto the middle hinge pin (5). Disconnect door switch wire (2). Make sure the door is aligned with the cabinet. Loosen hinge bolts (3). Replace the top hinge (4) installing hinge Lift off the top hinge (4).

  • Page 7: Remove Door Handle

    3-4 DOOR GASKET REMOVAL 3-3 REMOVE DOOR HANDLE 1. Remove door frame cover Starting at top of cover and working down, snap cover out and away from door. Loosen the set screws with the 3/32” allen wrench and remove the handle. NOTE: If the handle mounting fasteners need to be tightened or removes, use a 1/4”...

  • Page 8: Door Gasker Replacement

    3-5 DOOR GASKET REPLACEMENT 1. Insert gasket bracket clips 2) Press gasket into channels on the three remaining sides of door. 1) Insert gasket bracket edge beneath door frame edge. 2) Turn upper gasket bracket spring so that both spring ends are in the door channel.

  • Page 9: Pull Out Drawer

    3-7 PULL OUT DRAWER (a) HOW TO REMOVE PULL OUT DRAWER IMPORTANT: To avoid possible injury, product or When removing drawer door, do not hold it by the handle. Door could fall down and you may be property damage, you will need two people to perform injured grasp door with both hands as pictured below the following instructions.
  • Page 10 (b) HOW TO INSTALL PULL OUT DRAWER • Align the top holes of the rail cover with the top holes of IMPORTANT: To avoid possible injury, product or the door supports to assemble the rail cover. property damage, you will need two people to perform the following instructions.

  • Page 11: Fan And Fan Motor

    3-10-1 Refrigerator Compartment Lamp 3-8 FAN AND FAN MOTOR 1. Remove the freezer shelf. (If your refrigerator has an 1. Unplug the power cord from the outlet. icemaker, remove the icemaker first) 2. Remove refrigerator shelves. 2. Remove the plastic guide for slides on left side by 3.

  • Page 12: Adjustment

    4. ADJUSTMENT 4-2-3 PTC-Applied Circuit Diagram 4-1 COMPRESSOR Starting Method for the Motor • 4-1-1 Role The compressor intakes low temperature and low pressure gas from the evaporator of the refrigerator and compresses OVERLOAD PROTECTOR this gas to high-temperature and high-pressure gas. It then delivers the gas to the condenser.

  • Page 13: Olp (Overload Protector)

    4-4 TO REMOVE THE COVER PTC 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...

  • Page 14: Circuit Diagram

    5. CIRCUIT DIAGRAM CIRCUIT DIAGRAM PWB(PCB) ASSEMBLY,DISPLAY CON101 STEPPING C-FAN F-FAN MOTOR PK WH BK YL CON5 CON6 CON4 CON8 RT-SENSOR PWB(PCB) ASSEMBLY, MAIN R-DOOR PERCEPTION S/W CON7 F-DOOR PERCEPTION S/W DEF-SENSOR R-SENSOR F-SENSOR POWER SUPPLY CON1 CON2 CON3 CORD FRENCH DOOR HEATER GN/YL (GN)

  • Page 15: Troubleshooting

    6. TROUBLESHOOTING 6-1. COMPRESSOR AND ELECTRIC COMPONENTS (Rated voltage Remove PTC-Starter Power Source. from compressor and measure voltage between T erminal C of compressor and terminal 5 or 6 of PTC. No voltage. Reconnect. Check connection condition. Replace OLP. Advise customer that Applied voltage isn't power supply needs to in acceptable range.

  • Page 16: Ptc And Olp

    6-2 PTC AND OLP Separate PTC-Starter Observation value is Normal operation of compressor is impossible from Compressor and ±20% 115V/60Hz : 6.8 or poor. measure resistance between No. 5 and 6 of PTC-Starter with a T ester. (Figure 1) Replace PTC- The resistance value Starter.

  • Page 17: Other Electrical Components

    6-3 OTHER ELECTRICAL COMPONENTS • Not cooling at all Check for open short or Compressor Cause incorrect resistance readings doesn't run. in the following components a. Starting devices Short, open, or broken. Poor contact b. OLP or shorted. Coil open or shorted. c.
  • Page 18 6-4 SERVICE DIAGNOSIS CHART COMPLAINT POINTS TO BE CHECKED REMEDY No Cooling. • • Plug into the outlet. • Check if the power switch is set to OFF. • Set the switch to ON. • Check if the fuse of the power switch is shorted. •...

  • Page 19: Service Diagnosis Chart

    6-5 REFRIGERATION CYCLE • Troubleshooting Chart TEMPERATURE STATE OF STATE OF THE CAUSE REMARKS OF THE THE UNIT EVAPORATOR 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.
  • Page 20 6-5-1 Sealed System Diagnosis “Not Cooling” Complaint All components operating, No airflow problems, Not frosted up as a defrost problem problem has been isolated to sealed system area Frost None Partial Pattern? Equalization Equalization Test Test Very Fast Very Slow Very Slow Very Fast Fast...

  • Page 21: Operation Principle And Repair Method Of Icemaker

    7. OPERATION PRINCIPLE AND REPAIR METHOD OF ICEMAKER 7-1 OPERATION PRINCIPLE 7-1-1 Operation Principle of Icemaker Power On Start Position • Adjusts Ejector to Start Position with power on. Icemaking • Waits until water becomes cold after starting the Mode Icemaking operation.

  • Page 22: Ice Maker Functions

    7-2 ICE MAKER FUNCTIONS 7-2-1 Ice Making Mode 1. Icemaking refers to the freezing of supplied water in the ice trays. Complete freezing is assured by measuring the temperature of the Tray with icemaking SENSOR. 2. Icemaking starts after completion of the water fill operation. 3.

  • Page 23: Defect Diagnosis Function

    7-2-5 Function TEST 1. This is a compulsory operation for test, service, cleaning, etc. It is operated by pressing and holding the Cube Size button for 3 seconds. 2. The test works only in the Icemaking Mode. It cannot be entered from the Harvest or Fill mode. (If there is an ERROR, it can only be checked in the TEST mode.) 3.

  • Page 24: Description Of Function & Circuit Of Micom

    8. DESCRIPTION OF FUNCTION & CIRCUIT OF MICOM 8-1 FUNCTION 8-1-1 Function 1. When the appliance is plugged in, it is set to “4” for Refrigerator and “4” for freezer. You can adjust the Refrigerator and the Freezer control temperature by pressing the ADJUST button, 2.
  • Page 25 8-1-5 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.
  • Page 26 8-1-9 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 defect is repaired the defect code is removed and refrigerator returns to normal operation (RESET) 4.
  • Page 27 8-1-10 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. The test mode is operated by pressing two buttons at Display panel. 3.

  • Page 28: Pcb Function

    8-2 PCB FUNCTION 8-2-1 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: PART VA 1...
  • Page 29 8-2-2 Oscillation Circuit This circuit generates the base clock for calculating time and the synchro clock for transmitting data from and to the inside logic elements of the IC1 (MICOM). Be sure to use specified replacement parts, since calculating time by the IC1 may be changed.
  • Page 30 8-2-4 Load / Buzzer Drive & Open Door Detection Circuit 1. Load Drive Condition Check FRENCH DOOR DEFROSTING COMP LOAD TYPE LAMP HEATER 1, 2 / HEATER DEW HEATER Measurement Location (IC6) NO.14 NO.12 NO.11 NO.13 1V or below Condition - 29 -...
  • Page 31 2. Fan motor driving circuit (freezing compartment fan) 1. The circuit makes the Motor Fan OFF by cutting Off the power supplied to driver inside the Fan Motor when it is necessary. 2. This is a circuit to perform a temporary change of speed for the fan motor and applies DC voltage up to 7.5V ~ 16V to motor. 3.This circuit prevents over-driving the fan motor by cutting off power applied to the fan motor in the lock of fan motor by sensing the operation RPM of the fan motor.
  • Page 32 3. Cooling motor driving circuit (machine room) 1. This circuit makes standby power 0 by cutting off power supplied to Iss inside of the fan motor in the fan motor OFF. 2. This circuit prevents over-driving the fan motor by cutting off power applied to the fan motor in the lock of fan motor by sensing the operation RPM of the fan motor.
  • Page 33 4. Buzzer Drive Condition Check Condition Tone (Ding~Dong~) when the button on Alarm for open door Measure- the display is pushed. (beep-beep-beep) ment Location 0.05 s 0.2 s 0.1 s 0.5 s 0.5 s IC1 ( 2.63 kz (Ding~) 2.21 kz (Dong~) IC1 ( 2.63 kz (Beep~) 5.
  • Page 34 8-2-5 Temperature Sensor Circuit The upper CIRCUIT reads REFRIGERATOR temperature, FREEZER Temperature, and DEFROST-SENSOR temperature for defrosting and the indoor temperature for compensating for the surrounding temperature into MICOM. OPENING or SHORT state of each TEMPERATURE SENSOR are as follows: SENSOR CHECK POINT NORMAL (-30°C ~ 50°C)
  • Page 35 8-2-6 Refrigeration Compartment Stepping Motor Damper Circuit * The circuit shown below is the damper circuit to regulate the refrigerator temperature. 8-2-7 Temperature compensation & overcooling/undercooling compensation circuit Table of temperature compensation by cutting JUMP WIRE to easy SVC temperature adjustments +1deg, +1deg, -1deg, -1deg.
  • Page 36 8-2-8 Key Button Input & Display Light-On Circuit The circuit shown below determinates whether a function control key on the operation display is pushed. It also turns on the corresponding function indication LED (LED Module) SEVEN SEGMENT DISPLAY MODULE). The drive type is the scan type.

  • Page 37: Resistance Specification Of Sensor

    8-3 RESISTANCE SPECIFICATION OF SENSOR RESISTANCE OF REFRIGERATOR & TEMPERATURE DETECTED RESISTANCE OF FREEZER DEFROST SENSOR & ROOM SENSOR BY SENSOR SENSOR 22.3K -20°C -15°C 16.9K 13.0K 47.3K -10°C 38.4K -5°C 10.1K 0°C 7.8K 24.1K +5°C 6.2K +10°C 4.9K 19.5K +15°C 3.9K 15.9K...

  • Page 38: Troubleshooting

    - 37 -...
  • Page 39 - 38 -...

  • Page 40: Main Pwb Assembly And Parts List

    8-5 MAIN PWB ASSEMBLY AND PARTS LIST 8-5-1 Main PWB Assembly - 39 -...
  • Page 41 8-5-2 PWB Assembly, Display and parts list - 40 -...

  • Page 42: Pwb Diagram

    8-6 PWB DIAGRAM 8-6-1 PWB Main Assembly Part 1 - 41 -...
  • Page 43 Part 2 - 42 -...

  • Page 44: Exploded View

    #EV# 9.EXPLODED VIEW CASE PARTS CAUTION: use the part number to order part, not the position number. 103B 281A 402A 271C 282E 103A 410A 402A 409D 501F 503G 503F 271A 903D 503D 610A 282F 503C 503E 501A 409B 120B 411A 125D 145A 304A...
  • Page 45 #EV# FREEZER PARTS CAUTION: use the part number to order part, not the position number. 136B 131A 145C 248E 248F 145F 136A - 44 -...
  • Page 46 #EV# REFRIGERATOR PARTS CAUTION: use the part number to order part, not the position number. 146A 143E 140D 140B 140E 143E 140D 143E 140D 140B 140E 140B 140E 143F 142D 140B 142E 103E 103E 128A 103E 170A 167B 128B 154A 103E 151A 151A...
  • Page 47 #EV# DOOR PARTS CAUTION: use the part number to order part, not the position number. 241F 230A 230B 104E 241B 231A 233A 233D 231B 233B 233C 241A 212G 241C 233G 233H 241C 241C 233E 233F 244A 244A 212J 241C 212J 241C 241C 286A...
  • Page 48 #EV# WATER & ICEMAKER PARTS CAUTION: use the part number to order part, not the position number. 602A 600C 600A 622B 618A 627A 616E 623C 619C - 47 -...
  • Page 49 April, 2010 MFL62526028 Rev. 04...

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