LG LRFC25750ST Service Manual
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LG LRFC25750ST Service Manual

Refrigerator
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See also: Owner's Manual , User Manual
REFRIGERATOR
SERVICE MANUAL
CAUTION
BEFORE SERVICING THE UNIT,
READ THE SAFETY PRECAUTIONS IN THIS MANUAL.
MODEL:LRFC25750ST
LRFC21755SB
LRFC25750
LRFC21755ST
LRFC21755TT
http://biz.lgservice.com
C
OLOR COLOR: WESTERN BLACK
STAINLESS-STEEL
TITANIUM

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Summary of Contents for LG LRFC25750ST

  • Page 1 REFRIGERATOR SERVICE MANUAL CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. MODEL:LRFC25750ST OLOR COLOR: WESTERN BLACK LRFC21755SB LRFC25750 STAINLESS-STEEL LRFC21755ST TITANIUM LRFC21755TT...

  • Page 2: Table Of Contents

    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)............................

  • Page 3: Specifications

    1. SPECIFICATIONS 21 cu. ft. / 25 cu. ft. ITEMS SPECIFICATIONS ITEMS SPECIFICATIONS DOOR DESIGN Side Rounded VEGETABLE TRAY Opaque Drawer Type DIMENSIONS (inches) H) 21cu.ft COMPRESSOR PTC Starting Type H) 25cu.ft EVAPORATOR Fin Tube Type 278 (21cu.ft) CONDENSER Wire Condenser NET WEIGHT (pounds) 302 (25cu.ft) REFRIGERANT...

  • Page 4: Parts Identification

    2. PARTS IDENTIFICATION Digital Sensor Control Dairy Bin Refrigerator Light Egg Box Shelves Design-A-Door Design-A-Door Wine Holder Optibin Crisper Keeps fruits and vegetable fresh Design-A-Door and crisp Glide N Serve Customcube Icemaker Ice Bin Pull out Drawer Durabase Freezer Door Rack Divider (Tilting) - 4 -...

  • Page 5: Disassembly

    3. DISASSEMBLY 3-1 DOOR Freezer Door 1. Loosen the hex head bolts attaching the lower hinge to Refrigerator Door the body to remove the refrigerator door only. 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.

  • Page 6: Fan And Fan Motor

    3-2 FAN AND FAN MOTOR 3-4-1 Refrigerator Compartment Lamp 1. Unplug the power cord from the outlet. 1. Remove the freezer shelf. (If your refrigerator has an icemaker, remove the icemaker first) 2. Remove refrigerator shelves. 2. Remove the grille by pulling it out and by loosening a 3.

  • Page 7: Adjustment

    4. ADJUSTMENT 4-1 COMPRESSOR 4-2-3 PTC-Applied Circuit Diagram 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 8: Olp (Overload Protector)

    4-3 OLP (OVERLOAD PROTECTOR) 4-4 TO REMOVE THE COVER PTC 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 9: Circuit Diagram

    5. CIRCUIT DIAGRAM BETTER MODEL - 9 -...

  • Page 10: Troubleshooting

    6. TROUBLESHOOTING 6-1 COMPRESSOR AND ELECTRIC COMPONENTS (Rated Voltage Remove PTC-Starter Power Source. ±10%)? from Compressor and measure voltage between Terminal C of Compressor and Terminals 5 or 6 of PTC. OLP disconnected? No Voltage. Replace OLP. Check connection condition. Reconnect.

  • Page 11: Ptc And Olp

    6-2 PTC AND OLP Normal operation of Separate PTC-Starter Observation value is Compressor is from Compressor and 115V/60Hz : 6.8Ω±30% measure resistance impossible or poor. between No. 5 and 6 of PTC-Starter with a Tester. (Figure 14) Replace PTC- The resistance value Starter.

  • Page 12: Other Electrical Components

    6-3 OTHER ELECTRICAL COMPONENTS M 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 13: Service Diagnosis Chart

    6-4 SERVICE DIAGNOSIS CHART COMPLAINT POINTS TO BE CHECKED REMEDY No Cooling. • Is the power cord unplugged from the outlet? • Plug into the outlet. • Check if the power switch is set to OFF. • Set the switch to ON. •...

  • Page 14: Refrigeration Cycle

    6-5 REFRIGERATION CYCLE M 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 •...
  • Page 15 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 Fast Very Fast...

  • Page 16: Operation Principle & 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. Ice Making • Waits until water becomes cold after starting the Mode ice making operation.
  • Page 17 7-2 CONTROL METHOD ACCORDING TO FUNCTIONS 7-2-1 Start Position 1. After POWER OFF or Power Outage, check the EJECTOR's position with MICOM initialization to restart. 2. How to check if it is in place: - Check HIGH/LOW signals from HALL SENSOR in MICOM PIN. 3.
  • Page 18 7-2-4 Fill / Park Position 1. Once a normal harvest mode has been completed, the water solenoid will be activated. 2. The amount of water is adjusted by pressing the water supply control S/W. This changes the time allowed for fill as illustrated in the chart.
  • Page 19 7-2-5 Function TEST 1. This is a compulsory operation for TEST, SVC, cleaning, etc. It is operated by pressing the water supply control KEY for 3 seconds. 2. It operates in the Ice Making mode, but not in the Ice-Removing mode or water supply process. (If there is an ERROR, it can only be checked in the TEST mode.) 3.

  • Page 20: 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 "37" for Refrigerator and "0" for freezer. You can adjust the Refrigerator and the Freezer control temperature by pressing the ADJUST button. 2.
  • Page 21 8-1-6 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 1/2 seconds. These tones repeat every 30 seconds.
  • Page 22 8-1-9 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.
  • Page 23 8-1-10 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.
  • Page 24 8-1-11 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 25 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 26 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 specific replacement parts, since calculating time by the IC1 may be changed.
  • Page 27 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.12 NO.14 NO.15 NO.13 1V or below Condition 2.
  • Page 28 2. 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~) 3.
  • Page 29 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 30 8-2-7 Key Button Input & Display Light-On Circuit ➧ The circuit shown above determines 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 (SEVEN SEGMENT DISPLAY MODULE).
  • Page 31 8-3 RESISTANCE SPECIFICATION OF SENSOR RESISTANCE OF FREEZER RESISTANCE OF REFRIGERATOR & TEMPERATURE SENSOR DEFROST SENSOR & ROOM SENSOR - 20 ˚C (-4 °F) 22.3 KΩ 77 KΩ - 15 ˚C (5 °F) 16.9 KΩ 60 KΩ - 10 ˚C (14 °F) 13.0 KΩ...
  • Page 32 - 32 -...
  • Page 33 - 33 -...
  • Page 34 8-5 MAIN PWB ASSEMBLY AND PARTS LIST 8-5-1 Main PWB Assembly - 34 -...
  • Page 35 8-5-2 Replacement Parts List - 35 -...
  • Page 36 8-5-3 PWB Assembly, Display, And Parts List SW106 - 36 -...
  • Page 37 8-6 PWB DIAGRAM 8-6-1 PWB Main Assembly - 37 -...
  • Page 38 - 38 -...

  • Page 39: Exploded View & Replacement Parts List

    9. EXPLODED VIEW & REPLACEMENT PARTS LIST CASE PARTS CAUTION: Use the part number to order part, not the position number. 207B 103B 402A 271C 271B 103A 410A 207A 409D 271B 406D 501F 271A 402A 282F 503D 410G 145A 503C 610A 501A 409B...
  • Page 40 FREEZER PARTS CAUTION: Use the part number to order part, not the position number. 145C 136B 145F 248F 131A 237C 177B 136A - 40 -...
  • Page 41 REFRIGERATOR PARTS CAUTION: Use the part number to order part, not the position number. 147C 141B 141A 147B 147A 141B 141C 141A 141B 141A 141C 141B 141A 141C 146A 161E 167B 141C 161A 154A 161D 160B 151C 151A 161C 155J 161F 146B 210A...

  • Page 42: Door Parts

    DOOR PARTS CAUTION: Use the part number to order part, not the position number. 230B 230A 231B 233B 233C 233D 233A 231A 241A 241B 212G 241C 237A 241C 237A 244E 241C 244E 241C 241C 243A 243A 205C 249A 203A 281D 201A 205A 281D...
  • Page 43 ICE & MAKER PARTS CAUTION: Use the part number to order part, not the position number. 602A 600A 616E 623A 623B 619A - 43 -...
  • Page 44 P/No. 3828JL8031C APR., 2004 Printed in Korea...

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