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LG LMX21981 Series, Service Manual

The LG LMX21981 Series is a high-performance appliance designed with advanced features for efficient operations. To get the most out of this product, make sure to refer to the detailed Specification Sheet and user manual available for free download on our website.

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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:

VA1 is a part for preventing over voltage and noise. When 230V or higher power is applied, the inside elements are short-
circuited and broken, resulting in blowout of the fuse in order to protect the elements of the secondary part of the
TRANSFORMER.

PART

VA 1

CE 3

CE 4

CE 5

VOLTAGE

115 Vac

12 Vdc

15.5 Vdc

5 V

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Summary of Contents for LMX21981 Series

Page 1: ...ORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL REFRIGERATOR SERVICE MANUAL COLOR STAINLESS ST SUPER WHITE SW WESTERN BLACK SB MODEL LMX21981 01 LMX25981 01 w w w A p p l i a n t o l o g y o r g ...

Page 2: ...x Cover PTC Connector Tube Drier Assembly Thermistor Assembly PTC Overload Protect Door Assembly R efrigerator Left Door Assembly R efrigerator R ight Door Foam Assembly R efrigerator Door Foam Assembly R efrigerator PCB Assembly Connector Tube Guide Air S topper Door S topper Door Comressor S et Part Name LMX25981 01 w w w A p p l i a n t o l o g y o r g ...

Page 3: ...STMENT 18 19 COMPRESSOR 18 PTC STARTER 18 OLP OVERLOAD PROTECTOR 19 TO REMOVE THE COVER PTC 19 5 CIRCUIT DIAGRAM 20 6 TROUBLESHOOTING 21 25 COMPRESSOR AND ELECTRIC COMPONENTS 21 OTHER ELECTRICAL COMPONENTS 22 SERVICE DIAGNOSIS CHART 23 REFRIGERATION CYCLE 24 25 7 OPERATION PRINCIPLE REPAIR METHOD OF ICEMAKER 26 28 8 DESCRIPTION OF FUNCTION CIRCUITS ERROR CODES 29 45 9 EXPLODED VIEW REPLACEMENT PAR...

Page 4: ...pe COMPRESSOR Recipro EVAPORATOR Fin Tube Type CONDENSER Wire Condenser REFRIGERANT R 134a 140 g LUBRICATING OIL ISO10 280 ml DEFROSTING DEVICE SHEATH HEATER LAMP REFRIGERATOR LED Module 27 FREEZER LED Module 9 Description LMX21981 01 LMX25981 01 Depth w Handles A 30 in 34 1 4 in Depth w o Handles B 27 1 2 in 31 1 4 in Depth w o Door C 23 5 8 in 27 7 8 in Depth Total with Door Open D 42 1 4 in 46 ...

Page 5: ...ULAR DOOR BINS Three interchangeable bins can be arranged to suit your storage needs REMOVABLE ICE STORAGE BIN The ice storage bin can be removed to fill ice buckets coolers or pitchers INTERIOR LAMPS Two separate LED arrays light the freezer and refrigerator interiors FIXED DOOR BIN FIXED DOOR BIN 1 2 3 4 5 6 Ice Bank Ice Door w w w A p p l i a n t o l o g y o r g ...

Page 6: ...hen lifting hinge free of latch be careful that door does not fall forward 7 Place door inside facing up down onto a non scratching surface u u Right Door FIG 3 1 Open door Loosen top hinge cover screw 1 Lift up cover 3 2 Disconnect door switch wire harness 2 Remove cover 3 Disconnect wire harness 5 4 Rotate hinge lever 6 clockwise Lift top hinge 7 free of hinge lever latch 8 w w CAUTION When lift...

Page 7: ... Door Gasket Replacement 1 Insert gasket bracket clips 1 Insert gasket bracket edge beneath door frame edge 2 Turn upper gasket bracket spring so that the spring ends are in the door channel 3 Push in clip until you hear it snap securely into place 4 Push in remaining clip until you hear it snap securely into place Note Make sure that no part of gasket bracket edge protrudes from beneath door fram...

Page 8: ...l to adjust the bolt in the door hinge to adjust the height CCW to raise or CW to lower the height 3 4 FAN AND FAN MOTOR EVAPORATOR 1 Remove the freezer shelf If your refrigerator has an icemaker remove the icemaker first 2 Remove the plastic guide for slides on left side by unscrewing phillips head screws 3 Remove the grille by removing one screw and pulling the grille forward 4 Remove the Fan Mo...

Page 9: ...onnector with the Defrost Control assembly and replace the Defrost Control assembly after cutting the Tie Wrap Figure 11 CAUTION DO NOT ATTEMPT TO REMOVE THE MULLION REFRIGERANT LINES 3 6 LAMP Unplug Refrigerator or disconnect power at the circuit breaker If necessary remove top shelf or shelves 3 6 1 Refrigerator Compartment Lamp 1 Release 2 screws 2 Hold both ends with your both hands and pull i...

Page 10: ...ched by the dispensor 3 10 DISPLAY PCB As shown below remove 1 case PCB fixing screw Remove the display PCB fixing screw 3 11 ICE BUTTON ASSEMBLY 1 Remove the screw fixing the button lever 2 Push the spring from the hanging hook to remove it 3 Apply some pressure to the rib in direction and lift the button in direction 3 12 FUNNEL REPLACEMENT Pull down and forward Figure 16 Case PCB Display PCB Bu...

Page 11: ...15 ICE CORNER DOOR REPLACEMENT 1 Loosen the front screw as shown in the picture 2 Lift up the hinge with one hand 3 Pull out the Ice Corner Door with the other hand 3 16 ICEMAKER ASSEMBLY 1 Loosen two screws as shown in the first picture 2 Disconnect the wire harness ground screw replace theIcemaker assembly in the reverse order of removal 3 It separates a ground connection screw Button Lever hing...

Page 12: ...ews holding the auger motor cover shown in the picutres below 2 Grip the bottom of motor cover assembly and pull out it 3 Disconnect wire harness of motor cover assembly There is a auger motor on the back as shown in the picture Auger Motor 11 w w w A p p l i a n t o l o g y o r g ...

Page 13: ...art slightly 3 Take the Ice Bin out slowly 3 21 HOW TO INSERT A DOOR ICE BIN 1 Insert the Ice Bin slightly tilting it to avoid touching the Icemaker especially ice maker lever Insert the ice bucket carefully avoid contacting the automatic shut off arm 12 1 2 w w w A p p l i a n t o l o g y o r g ...

Page 14: ...hook it from the rail support and remove Pull both rails to full extension Step 5 First Remove the gear from the left side first by releasing the tab behind the gear place a screwdriver between the gear and the tab and pull up on the gear Second Remove the center rail Third Remove the gear from the right side by following the same steps for the left side NOTE THIS TAB MUST BE PUSHED IN TO RELEASE ...

Page 15: ...ushing the rails all the way into the freezer section Pull the rails back out to full extension Step 6 Reinstall the two screws into the guide rails one from each side Step 3 Insert the rail into the left side gear and insert the gear into the clip Step 5 Reinstall the freezer door by inserting the rail tabs into the guide rail Step 7 Reinstall the lower basket and close the freezer door 14 w w w ...

Page 16: ...sing a short screwdriver loosen one SCREW in DRAIN PIPE ASSEMBLY and one connected to the MOTOR COVER 2 Pull and separate the FAN ASSEMBLY and MOTOR turning counterclockwise based on the MOTOR SHAFT The assembly is in the reverse order of the disassembly and take special care for the following details 1 Be careful not to bend the tube during assembly 2 Press the WATER DISPENSER button until water ...

Page 17: ...nsion Remove the drawer and Ice Bin lifting the basket from the rail system 3 26 BOTTOM DRAWER To remove the freezer drawer pull the drawer open to full extension Remove the lower DuraBase basket by lifting the basket from the rail system 16 w w w A p p l i a n t o l o g y o r g ...

Page 18: ... caution when performing repairs 4 1 1 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 the compressor dry If the Compressor gets wet in the rain or a damp environment and rust forms in the pin of...

Page 19: ...normal operation of the OLP do not turn the adjustment screw of the OLP in any way 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 therm...

Page 20: ...5 CIRCUIT DIAGRAM 19 w w w A p p l i a n t o l o g y o r g ...

Page 21: ...ly voltage rating with 10 Applied voltage isn t in acceptable range 115V 10 Remove TSD Starter from compressor and measure voltage between terminal C of compressor and terminal 5 or 6 of TSD Check resistance between M C S C and M S in motor compressor Check resistance of two terminals in TSD Starter Check resistance of two terminals in OLP Check the power supply under load Compressor attempting to...

Page 22: ...om compressor and measure resistance between No 5 and 6 of PTC Starter with a tester Figure 19 Separate OLP from compressor and check resistance value between two terminals of OLP with a tester Figure 20 Observation value is 115V 60Hz 6 8Ω 30 The resistance value is 0Ω short or open Check another electric component Replace OLP Replace TSD Starter Figure 19 Figure 20 w w w A p p l i a n t o l o g y...

Page 23: ...p 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 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 ...

Page 24: ...e normal amount of cool normally refrigerant and repairing the leak PARTIAL Freezer Flowing sound of refrigerant A little higher Normal discharging of the CLOG compartment and is heard and frost forms than ambient refrigerant Refrigerator don t in inlet only temperature The capillary tube is faulty cool normally WHOLE Freezer Flowing sound of refrigerant Equal to ambient Normal discharging of the ...

Page 25: ...icient Compressor Partial Restriction Complete Restriction Equalization Test Condenser Temperature None Very Fast Very Slow Very Slow Hotter than Normal Air Low Side Leak Loss of Change Compressor Not Pumping Cap Tube Sound Room Temperature Trace of Oil Undercharge Leak Yes No Faint Fast None to Weak The equalization test is trying to restart a compressor using a start kit after it has been operat...

Page 26: ...omes ICE after starting the icemaking operation Runs MOTOR to drop ice from the tray into the ICE BIN During harvest mode check if the ice bin is full Performs Ice Making Mode after supplying water by operating the SOLENOID in ICE VALVE To operate LINE and SERVICE press and hold the Fill Key for 3 seconds The icemaker will run through 3 stages Harvest Fill Icemaking Reaches Start Position Cube Siz...

Page 27: ...orage bin while rotating with the EJECTOR A Ice storage bin is full The EJECTOR stops heater off B Ice storage bin is not full The EJECTOR rotates twice to open for ice If the EJECTOR does not rotate once within 5 minutes in B mode separate heater control mode starts operating to prevent the EJECTOR from being constrained It is recommended that the user open for ice to return to normal mode 7 2 3 ...

Page 28: ...agnosis TABLE 7 3 DEFECT DIAGNOSIS FUNCTION 7 3 1 ERROR CODES shown on Ice Maker water supply control panel 27 STAGE ITEMS INDICATOR REMARKS 1 2 3 4 5 6 HEATER MOTOR HALL IC I HALL IC II VALVE Reset Five seconds after heater starts a heater will go off if the temperature by sensor is higher than 10 C Five seconds after heater starts you can confirm that a motor is moving Check if Ice Bin is full o...

Page 29: ... locked state The buzzer sound other control buttons and the dispenser are deactivated 4 To release from the locked state press and hold the LOCK button again for 3 seconds 8 1 3 Filter condition display function 1 There is a replacement indicator for the filter cartridge on the dispenser 2 Water filter needs replacement once six months or of using water filter 3 Water Filter icon turn on to tell ...

Page 30: ...as belows Normal status When dispenser is operated DISPENSER LIGHT is ON ON status DISPENSER LIGHT is on continuously 8 1 7 CONTROL OF FREEZER FAN MOTOR 1 Freezer fan motor has high and standard speeds 2 High speed is used at power up for Ice Plus and when refrigerator is overloaded Standard speeds is used for general purposes 3 To improve cooling speed the RPM of the freezer fan motor change from...

Page 31: ...s run for more than 90 minutes Ice Plus will run for two hours after the defrost is completed 3 If ICE PLUS is pressed during defrost ICE PLUS Icon is on but this function will start seven minutes after defrost is completed and it shall operate for three hours 4 If Ice Plus is selected within seven minutes after compressor has stopped the compressor compressor delays seven minutes shall start afte...

Page 32: ...rosting won t function if its sensor is defective wires are cut or short circuited 8 1 13 Defect Diagnosis Function 1 Automatic diagnosis makes servicing the refrigerator easy 2 When a defect occurs the buttons will not operate 3 When the defect CODE removes the sign it returns to normal operation RESET 4 The defect CODE shows on the Refrigerator and Freezer Display LED check function If simultane...

Page 33: ...efrosting sensor is not over 46 F 8 C it is caused It is caused when F B signal isn t over 65 seconds during BLDC FAN motor operating It is caused when F B signal isn t over 65seconds during BLDC FAN motor operating It is caused when F B signal isn t over 65seconds during BLDC FAN motor operating Communication Error between Micom of Main PCB and Display Micom Normal operation of Display Each Senso...

Page 34: ...1 Function Test 33 MODE OPERATION FUNCTION REMARKS TEST1 TEST2 TEST3 RESET Push test button one time at main PCB controller Push Test button one in TEST PCB MODE1 Push Test button one in TEST PCB MODE2 Push Test button one in TEST PCB MODE3 1 peration of the COMPRESSOR and FAN Freezer Condenser Icing 2 Stepping DAMPER OPEN 3 Defrosting HEATER OFF 4 DISPLAY LED all ON 1 peration of the COMPRESSOR a...

Page 35: ...and IC 5 Vdc The voltage for each part is as follows VA1 is a part for preventing over voltage and noise When 230V or higher power is applied the inside elements are short circuited and broken resulting in blowout of the fuse in order to protect the elements of the secondary part of the TRANSFORMER PART VA 1 CE 3 CE 4 CE 5 VOLTAGE 115 Vac 12 Vdc 15 5 Vdc 5 V w w w A p p l i a n t o l o g y o r g ...

Page 36: ...n Pin2 3 of con4 MOTOR OFF 2V or less MOTOR ON 13V 15V 35 Circuit Pin Number Pin Number Output Voltage I Maker Pilot Valve Con3 Pin3 Con3 Pin2 115 VAC R R Door R L Door Heater Con3 Pin8 Con3 Pin2 115 VAC Def Heater Con3 Pin10 Con3 Pin2 115 VAC Water Pilot Valve Con3 Pin11 Con3 Pin2 115 VAC Compressor Con3 Pin12 Con3 Pin2 115 VAC LAMP R Con3 Pin9 Con3 Pin2 115 VAC LAMP F Con3 Pin7 Con3 Pin2 115 VAC...

Page 37: ...2 3 Machine compartment fan 2 4 Icing compartment fan Pin8 9 of con4 MOTOR OFF 2V or less MOTOR ON 10V 14V Pin5 6 of con4 MOTOR OFF 2V or less MOTOR ON 10V 14V 36 w w w A p p l i a n t o l o g y o r g ...

Page 38: ...re into MICOM Opening or short state of each temperature sensor are as follows Closed 5 V Open 0V Freezer Refrigerator Door Measurement Location Pin 11 12 of con4 Ref Door Pin 5 6 of con6 Fre Door 37 SENSOR CHECK POINT NORMAL 30 C 50 C SHORT CIRCUITED OPEN Freezer sensor POINT Voltage Refrigerator sensor POINT Voltage 0 5 V 4 5 V 0 V 5 V Defrosting sensor POINT Voltage Room Temperature sensor POIN...

Page 39: ...NSOR SUPER FROST SENSOR R1 R2 SENSOR after disconnect CON5 of PWB ASSY MAIN TEMPERATURE RESISTANCE OF FREEZER ICING RESISTANCE OF REFRIGERATOR SENSOR DEFROST SENSOR ROOM SENSOR 20 C 22 3 KΩ 77 KΩ 15 C 16 9 KΩ 60 KΩ 10 C 13 0 KΩ 47 3 KΩ 5 C 10 1 KΩ 38 4 KΩ 0 C 7 8 KΩ 30 KΩ 5 C 6 2 KΩ 24 1 KΩ 10 C 4 9 KΩ 19 5 KΩ 15 C 3 9 KΩ 15 9 KΩ 20 C 3 1 KΩ 13 KΩ 25 C 2 5 KΩ 11 KΩ 30 C 2 0 KΩ 8 9 KΩ 40 C 1 4 KΩ 6...

Page 40: ...lose the damper push test button twice 8 2 5 Dispenser Drive Circuit 39 Circuit Pin Number Pin Number Output Voltage Auger Motor Con1 Pin12 Con1 Pin4 115 VAC Solenoid Cube Con1 Pin11 Con1 Pin4 115 VAC Pilot Water Valve Con1 Pin10 Con1 Pin4 115 VAC Solenoid Dispenser Con1 Pin9 Con1 Pin4 115 VAC Heater Con1 Pin7 Con1 Pin4 115 VAC w w w A p p l i a n t o l o g y o r g ...

Page 41: ...2 6 LED in Refrigerator Freezer room Apply for LED Model Optional CON6 12V GND 14 15 Circuit Pin Number Pin Number Output Voltage LED Module Con6 Pin14 Con6 Pin15 12 VDC w w w A p p l i a n t o l o g y o r g ...

Page 42: ...facetemperatureof thecondenserpipe USETESTMODE1 forcedCOOLING Checktheamountoffrost stickingonthe EVAPORATOR oftheRefrigerator SENSOR Checkthesealwhenthe doorisclosed POWERSOURCEis poor Appliedvoltageerror CONNECTOR connectionispoor TRANSFUSEisopen COMPRESSORlocked orblocked OLP PTCispoor COMPRESSORRELAY ispoor THECONNECTING WIREispoor Refrigerantleakage FANMOTORispoor CONNECTINGWIREis poor DEFROS...

Page 43: ...heckDRAINPIPE Makesurethat DEFROSTSENSORis connected Makesurethat FREEZER REFRIGERATOR DOORisclosed FANMOTORispoor Passageofcoolairis blocked EVAfrozen Doorlinerdamaged HEATERdisconnection TEMPERATUREFUSE disconnection Connectionispoor DEFROST SENSORis poor HEATERRELAYispoor DRAINPIPEisblocked Connectionispoor DOORdoesnotclose properly MakesuretheDOOR isattached ReplaceFANMOTOR Removeimpurities Se...

Page 44: ...8 4 MAIN PWB ASSEMBLY AND PARTS LIST 8 4 1 Main PWB Assembly 43 w w w A p p l i a n t o l o g y o r g ...

Page 45: ...8 4 2 Dispenser Drive PWB Assembly 44 w w w A p p l i a n t o l o g y o r g ...

Page 46: ...3B 207A 315B 315B 315C 315C 408A 158A 503D 405F 404A 405C 407B 407A B04 S17 S15 158B 145B 120B 145A 610A 405B 329A 103C 402A S10 S12 S11 S18 313A S08 282G 282F B01 S03 S03 B01 S14 262B B02 B02 S14 262H 249M 249L 310B 302B 406D 402A 249D 249C 411A 120A 503E S11 409D 409E 501F 332C 406B 312C 271B 271D 410G 106A 106A 610E 303A 303B 303C 304A 323B 319A 319C 420A 309B 329C 319C S20 w w w A p p l i a n ...

Page 47: ...FREEZER PARTS CAUTION Use the part number to order part not the position number 136B 250G 250G 251A 251B 203D 203C 131A 136A 237C w w w A p p l i a n t o l o g y o r g ...

Page 48: ...part number to order part not the position number on some models 142A 140A 142B 142D 141A 141C 141B 141A 141C 141B 141A 141C 141B 162B 145D 162A 147C 147A 146E 151A 151C 161B 141D 161C 151B 154A 161A w w w A p p l i a n t o l o g y o r g ...

Page 49: ...3A 233D 231A 233B 233C 231B 230B 234A 234C 241A 241B 241C 212G 230A 241G 241E 241H 241J 312B 244A 244A 234B 234D 241D B06 B06 B06 B06 603C 203A B06 B06 250A 250B 249E 249J 250B 249E 249J 249F 250B 249K 212D 201A 203B B06 B06 250A 249F 250B 249K 212D 201B 200A 200B 243D 243A 262C 243C 243B 262C 262E w w w A p p l i a n t o l o g y o r g ...

Page 50: ... PARTS CAUTION Use the part number to order part not the position number 405A 275A 276A 279A 279G 279D 279J 279H 500C 281B 281A 402C 279E 278D 279B 500E 501A 279C 500D 501D w w w A p p l i a n t o l o g y o r g ...

Page 51: ...KER PARTS CAUTION Use the part number to order part not the position number B B J 619E 603B 619A 627A 627B 616F 616D 625A 616G 623B 616G 623B 616J 603C 616D 616J 617A S31 w w w A p p l i a n t o l o g y o r g ...

Page 52: ...PARTS CAUTION Use the part number to order part not the position number 630C 6 606A 614A 630E 630D 630L 630N 630M 630K 630A 630C 630F 630B 611A 600A 630J 600B 612A 630H 630G w w w A p p l i a n t o l o g y o r g ...

Page 53: ...P No MFL48178802 SEP 2008 Printed in Korea w w w A p p l i a n t o l o g y o r g ...

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