LG LMX21981 Series Training Manual
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LG LMX21981 Series Training Manual

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LG TRAINING MANUAL
LG TRAINING MANUAL
Four Door Refrigerator LMX21981**
Fall 2008

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  • Page 1 LG TRAINING MANUAL LG TRAINING MANUAL Four Door Refrigerator LMX21981** Fall 2008...
  • Page 2 Published August 2008 by LG Electronics USA Trainng Center Copyright © 2008 LG Electronics of Alabama, Inc. hone ontaCts Contact Number Hours of Operation Customer Service (800) 243-0000 24/7 - 365 days a year Technical Support (800) 847-7597 7am-7pm Mon-Fri / Sat 8-2 CST...

  • Page 3: Table Of Contents

    LMX21981xx REFRIGERATOR LMX21981xx (REFRIGERATOR) Contents Safety Notices and Warnings Specifications Parts Identification Installation Weight Hazard Leveling Flooring Handle Removal Door Removal (Right and Left Doors) Water Tube Connection Water Line Installation Kit Operation (Control Panel and Display) Adjusting the Temperatures and Displays Operating the Dispenser Dispensing Crushed or Cubed Ice Dispensing Water...
  • Page 4 LMX21981xx REFRIGERATOR Icemaker (continued) Error Codes Main Control Board Conductor Reference (Photo) Power From Board To Icemaker Icemaker Removal Icemaker Service Bulletin Pilot Valve Assembly Ice and Water Valves Fan and Motor Disassembly News Flash Freezer Fan Ice Room Fan Condenser Fan Evaporator and Ice Room Fan Access Freezer Section Mullion...

  • Page 5: Lmx21981Xx Refrigerator

    The manufacturer and seller are not to be held responsible for any liability incurred from its use. COMPLIANCE The responsible party for this device’s compliance is LG Electronics Alabama, Inc.; 201 James Record Road, Huntsville, AL, 35813. LMX21981xx...

  • Page 6: Specifications

    LMX21981xx REFRIGERATOR SPECIFICATIONS LMX21981xx Page 4 TRAINING MANUAL...
  • Page 7 LMX21981xx REFRIGERATOR LMX21981xx Page 5 TRAINING MANUAL...

  • Page 8: Parts Identification

    LMX21981xx REFRIGERATOR PARTS IDENTIFICATION LMX21981xx Page 6 TRAINING MANUAL...

  • Page 9: Installation

    LMX21981xx REFRIGERATOR INSTALLATION WEIGHT HAZARD! The refrigerator weighs as much as 325 pounds (148 kg). We recommend a minimum of two people for moving and servicing this refrigerator. LEVELING Be sure the floor is level and strong enough to support the refrigerator. Unstable installation or unleveled flooring may cause vibration, noise, and poor door operation.

  • Page 10: Flooring

    LMX21981xx REFRIGERATOR FLOORING The refrigerator must be installed on a solidly constructed floor to minimize noise and vibration. The refrigerator must be level. If necessary, adjust the leveling legs under the front of the refrigerator to compensate for variations in the flooring. This is easier if the refrigerator is tipped slightly backward to take the weight off the legs.

  • Page 11: Door Removal (Right And Left Doors)

    LMX21981xx REFRIGERATOR DOOR REMOVAL Disconnect the electrical supply and shut off the water to the refrigerator before installing or servicing. Do not put your hands, feet, fingers, or metal (conductive) items into the air vents, the base grille (kick plate), or bottom of the refrigerator. You could be injured or shocked. If the entrance door is too small to accommodate the refrigerator, you can remove the doors and pull the refrigerator into the room sideways.
  • Page 12 LMX21981xx REFRIGERATOR LEFT REFRIGERATOR DOOR Disconnect the hose at the top right corner (facing the back) by removing the release clip and pressing the release ring. The tube will be pulled out with the door when it is removed. Open the door to 90°. The door must be opened to 90°...

  • Page 13: Water Tube Connection

    LMX21981xx REFRIGERATOR WATER TUBE CONNECTION The water tube connections must be properly assembled to avoid leaking. Insert the tube into the connector until only one of the printed lines is visible. Pull on the tube slightly to ensure proper insertion and retention. Insert the retainer clip under the release ring.

  • Page 14: Water Line Installation Kit

    Often, these kits include a piercing saddle-type valve that allows connection to the water line without the need for plumbing skills. LG does not recommend the use of this type valve because it often fails to provide sufficient water...
  • Page 15 LMX21981xx REFRIGERATOR Various connector types are available. These illustrations show a saddle valve with the water line connected using a compression fitting at each end. The additional coil of tubing (approx- imately 7 feet or 2.1 m) is to allow pulling the refrigerator out for servicing or cleaning.

  • Page 16: Operation (Control Panel And Display)

    LMX21981xx REFRIGERATOR OPERATION 1. LED DISPLAY The LED display shows the temperature settings, dispenser options, water filter, door alarm, and locking status messages. 2. ICE TYPE BUTTON The ICE TYPE button is used to select Cubed Ice or Crushed Ice. 3.
  • Page 17 LMX21981xx REFRIGERATOR THE LED DISPLAY The LED display shows the temperature settings, dispenser options, water filter, door alarm, and locking status messages. 1. DISPENSER SELECTION INDICATOR Shows that Cubed ice or Crushed Ice selection will be dispensed when the push switch is pressed.

  • Page 18: Adjusting The Temperatures And Displays

    LMX21981xx REFRIGERATOR ADJUSTING THE TEMPERATURE AND DISPLAYS Adjust Freezer Temperature To adjust the temperature in the freezer compartment, press the FREEZER button to cycle through the range of available settings. Adjust Refrigerator Temperature To adjust the temperature in the refrigerator compartment, press the REFRIGERATOR button to cycle through the range of available settings.

  • Page 19: Operating The Dispenser

    LMX21981xx REFRIGERATOR OPERATING THE DISPENSER DISPENSING CRUSHER OR CUBED ICE Press the ICE TYPE button to illuminate the Crushed Ice icon. Press the push ice switch with a glass or other container and crushed ice will be dispensed. Press the ICE TYPE button to illuminate the Cubed Ice icon.

  • Page 20: Setting The Dispenser Lock

    LMX21981xx REFRIGERATOR CAUTION When filling the container with a small opening, use it near the opening of the water or ice dispenser as close as possible. SETTING THE DISPENSER LOCK Press and hold the ALARM/LOCK button for three seconds to lock the dispenser and all of the other control panel functions.

  • Page 21: Resetting The Filter Indicator

    LMX21981xx REFRIGERATOR RESETTING THE FILTER INDICATOR Press and hold the LIGHT/FILTER button for more than 3 seconds to reset the filter indicator after the water filter has been replaced. NOTE: Replace the filter when the water filter indicator light reaches 0 or whenever the water or ice cube taste deteriorate noticeably.

  • Page 22: Replacing The Water Filter

    LMX21981xx REFRIGERATOR REPLACING THE WATER FILTER Replace the filter when the water filter indicator decrements to 0 or the water dispenser or icemaker noticeably decrease production. Rotate the knob of the old cartridge counterclockwise. When the cartridge is released, you will feel it click out of place. NOTE: Replacing the filter causes a small amount of water (around 1 oz.

  • Page 23: Disassembly

    LMX21981xx REFRIGERATOR DISASSEMBLY REMOVING AND REPLACING REFRIGERATOR DOORS CAUTION: Before you begin, unplug the refrigerator. Remove food and bins from doors. Left Door – FIGURE 2 (Next Page) Disconnect water supply tube by pushing back on the disconnect ring (4). See FIGURE 1, next page.
  • Page 24 LMX21981xx REFRIGERATOR LMX21981xx Page 22 TRAINING MANUAL...

  • Page 25: Icemaker Door

    LMX21981xx REFRIGERATOR ICEMAKER DOOR Loosen the front screw (nearest the hinge) of the bracket. Lift the hinge with one hand. It might be necessary to loosen the rear screw slightly. Lift the icemaker door out of the lower hinge with the other hand. REMOVE and REPLACE the PULLOUT FREEZER DRAWER Open the freezer door.
  • Page 26 LMX21981xx REFRIGERATOR PULLOUT FREEZER DRAWER, continued Remove the two screws from the guide rails (one from each side.) Lift the freezer door up to unhook it from the rail support and remove. Pull both rails to full extension. 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.

  • Page 27: Reinstall The Pullout Freezer Door

    LMX21981xx REFRIGERATOR FOLLOW THESE STEPS TO REINSTALL Reinstall the right side gear into the clip. Insert the rail into the right side gear. The gears do not need to be perpendicular to each other. Insert the rail into the left side gear, and insert the gear into the clip.
  • Page 28 LMX21981xx REFRIGERATOR REINSTALLATION, continued The rail system will align itself by pushing the rails all the way into the freezer section. Pull the rails back out to full extension. Reinstall the freezer door by inserting the rail tabs into the guide rail. Reinstall the two screws into the guide rails (one from each side).

  • Page 29: Dispenser Assembly

    LMX21981xx REFRIGERATOR DISPENSER ASSEMBLY Remove the tray. Lift out the grate. Then pull the tray out past the stops without breaking it. NOTE: Pay close attention to the clip that is located under the tray. Look at how it is installed in case it comes out while removing the dispenser assembly.
  • Page 30 LMX21981xx REFRIGERATOR DISPENSER ASSEMBLY, continued Release the side clips. Loosen all four edges. Pull the dispenser assembly forward and remove all the connectors. LMX21981xx Page 28 TRAINING MANUAL...

  • Page 31: Display

    LMX21981xx REFRIGERATOR DISPENSER ASSEMBLY, continued Back view of dispenser. Display PCB. DISPLAY WHITE/BLACK – 12V to Display Board BRIGHT ORANGE – Ground BROWN – RX (RX to Ground Receives Variable V Pulse) RED – TX (TX to Ground Transmits Variable V Pulse) LMX21981xx Page 29...

  • Page 32: Refrigerator Led

    LMX21981xx REFRIGERATOR REFRIGERATOR LED BLUE/WHITE – 12V from Refrigerator Door Switch (CON 5) BLU/WH to PK(CON 6) or BOR Door CLOSED – 0 V Door OPEN – 12 V BLUE/WHITE – 12V from PC to WHITE on LED (CON 4) BLUE/WH to PK(CON 6) or BOR Door CLOSED –...

  • Page 33: Icemaker

    LMX21981xx REFRIGERATOR ICEMAKER ICEMAKING MODE The icemaking cycle begins with the water fill operation. When the water is frozen, as determined by a sensor incorporated in the tray, the cubes are ejected, and the process is repeated. The sensor triggers the cycle when it reaches 16 to 19° F (-7° C), approximately 55 minutes after the start of the cycle.

  • Page 34: Icemaker Cycle

    LMX21981xx REFRIGERATOR ICEMAKER CYCLE TEST MODE Press and hold the cube size button for more than three seconds to put the icemaker into test mode. The test cycle can be used to diagnose icemaker issues and to clean it. The test mode can be started only in ice making mode; it cannot be accessed while the icemaker is filling or ejecting.

  • Page 35: Diagnostic Chart

    LMX21981xx REFRIGERATOR If the icemaker does not operate normally during test mode, turn it off. Check it and repair as necessary or replace. When the test cycle is complete, the icemaker reverts to MICOM control and assumes the factory default fill setting. DIAGNOSTIC CHART ERROR CODES LMX21981xx...

  • Page 36: Main Control Board Conductor Reference (Photo)

    LMX21981xx REFRIGERATOR MAIN CONTROL BOARD CONNECTOR REFERENCE LMX21981xx Page 34 TRAINING MANUAL...

  • Page 37: Power From Board To Icemaker

    LMX21981xx REFRIGERATOR POWER from BOARD to ICEMAKER RED – 120V supply to icemaker fill valve in the door (when activated) BLUE – Constant neutral YELLOW – Constant 120V supply to icemaker and refrigerator door BLACK – 120 V to compressor (when activated) GREY –...
  • Page 38 LMX21981xx REFRIGERATOR ICEMAKER REMOVAL, continued Separate the two electrical connectors. Remove the upper screws. Remove the ground screw. Replace it in the icemaker assembly in the event you need to reuse it or require it in the replacement unit. Separate the 4-pin electrical connector. LMX21981xx Page 36 TRAINING MANUAL...

  • Page 39: Icemaker Service Bulletin

    LMX21981xx REFRIGERATOR ICEMAKER SERVICE BULLETIN LMX21981xx Page 37 TRAINING MANUAL...
  • Page 40 LMX21981xx REFRIGERATOR LMX21981xx Page 38 TRAINING MANUAL...
  • Page 41 LMX21981xx REFRIGERATOR LMX21981xx Page 39 TRAINING MANUAL...

  • Page 42: Pilot Valve Assembly

    LMX21981xx REFRIGERATOR PILOT VALVE ASSEMBLY Turn off the water. Remove the water line from the valve by removing the release guard clip and pressing the collet (release ring.) Separate the mechanical cover and remove the screw that holds the valve assembly to the refrigerator. Separate the housing.

  • Page 43: Ice And Water Valves

    LMX21981xx REFRIGERATOR ICE AND WATER VALVES Remove the tilt drawer (door bin.) Remove the valve access panel. Reservoir (tubing) and valves. Ice and water valves. LMX21981xx Page 41 TRAINING MANUAL...

  • Page 44: Fan And Motor Disassembly

    LMX21981xx REFRIGERATOR FAN and MOTOR DISASSEMBLY Using a short screwdriver, loosen one screw in the drain pipe assembly and another one connected to the motor cover. Pull the fan blade off its shaft by turning it counterclockwise as you pull. NEWS FLASH The fan motor is a variable speed DC motor.

  • Page 45: Ice Room Fan

    LMX21981xx REFRIGERATOR ICE ROOM FAN RED – SUPPLY (Positive) BLUE – GROUND BROWN – SIGNAL (Positive) While Operating: RD to BL – Approx. 11.1 V BL to BR – 2.5 V Door OPEN or OFF – 0 V CONDENSER FAN SKY BLUE –...
  • Page 46 LMX21981xx REFRIGERATOR EVAPORATOR and ICE ROOM FAN ACCESS, continued Release the tabs on the back panel and pull the panel out toward you. Separate the connectors and you can remove the entire panel assembly from the freezer. NOTE: The ice room fan supplies air to the ice room through ducting in the cabinet.

  • Page 47: Freezer Section Mullion

    LMX21981xx REFRIGERATOR FREEZER SECTION MULLION The service manual makes no reference to this loop. It would be very easy for a technician to break these refrigerant lines when attempting to access the fan motors or defrost components. CAUTION DO NOT ATTEMPT TO REMOVE THE MULLION;...

  • Page 48: Refrigerator Module Connector

    LMX21981xx REFRIGERATOR REFRIGERATOR MODULE CONNECTOR HOW IT WORKS On this new 4-door refrigerator, the LED control board has been incorporated into the main PWB Assembly. The operation and diagnosis is easier than previous refrigerators with a separate LED control board assembly. This refrigerator has 2 LED modules, one in the refrigerator section and one in the freezer section.
  • Page 49 LMX21981xx REFRIGERATOR HOW IT WORKS, continued Operationally, the door monitoring switches are open when the doors are closed. When doors are closed and monitoring switches for the refrigerator and freezer doors are open, will be measured across the control board terminals referenced above and 5 V will be measured across the open terminals of the perception section of the door switches.

  • Page 50: Refrigerator Led Module

    LMX21981xx REFRIGERATOR REFRIGERATOR LED MODULE White to Black Door closed White to Black Door open 12 V LMX21981xx Page 48 TRAINING MANUAL...
  • Page 51 LMX21981xx REFRIGERATOR REFRIGERATOR LED MODULE, continued Red to Black 12 V Constant The freezer LED assembly is similar to the refrigerator, but smaller. The repair procedure is the same. SKY BLUE – 12 VDC supply to all LED door switches WHITE Wires GRAY –...

  • Page 52: Defrost Control Assembly

    LMX21981xx REFRIGERATOR DEFROST CONTROL ASSEMBLY The defrost sensor consists of a temperature sensor and a thermal fuse. This assembly is attached to the metal side of the evaporator and senses temperature. It turns off the defrost heater at 46 °F (8°...

  • Page 53: Thermistor Tips

    LMX21981xx REFRIGERATOR DEFROST CONTROL ASSEMBLY, continued The orange leads go to the defrost sensor on CONNECTOR 6. Using your ohmmeter, read the resistance of the sensor to determine the temperature. In this example, 60.5 kΩ indicates 5° F. (See thermistor chart, page 74.) THERMISTOR TIPS •...

  • Page 54: Thermistors (Sensors)

    LMX21981xx REFRIGERATOR THERMISTORS (SENSORS) Orange to Orange – Defrost (0.5 – 4.5 or Resistance) White to White – Refrigerator (0.5 – 4.5 or Resistance) Blue to Blue – Freezer (0.5 – 4.5 V Resistance) Thermistors are NTC (Negative Temperature Coefficient). As the temperature DECREASES, the resistance INCREASES.

  • Page 55: Multi-Duct

    LMX21981xx REFRIGERATOR MULTI-DUCT Pry out the upper and lower caps and remove the two screws. Separate the electrical connectors when the duct is removed. Replace the foam gasket if it is damaged. Be sure the newly adhered gasket does not interfere with damper operation.

  • Page 56: Stepper Motor

    LMX21981xx REFRIGERATOR STEPPER MOTOR Blue to Black – Pulsing mV @ 75Hz while operating (400 Ω) Yellow to Red – Pulsing mV @ 75Hz while operating (400 Ω) 120 V loads switching relays COMPRESSOR PTC (Positive Temperature Coefficient) The PTC (Positive Temperature Coefficient) is a non-contact ceramic semiconductor that uses BaTiO .

  • Page 57: Compressor Olp (Overload Protector)

    LMX21981xx REFRIGERATOR The PTC must be allowed to cool before the system can be restarted. Within the sealed system, it takes approximately 5 minutes for the pressure to equalize so the compressor can restart. When the PTC cools sufficiently, the compressor can start again. If the compressor attempts to restart before the PTC has cooled, the PTC will allow current to flow to only the main winding and the OLP will open because of the over current condition.

  • Page 58: Replacing The Olp

    LMX21981xx REFRIGERATOR REPLACING THE OLP Remove the rear cover of the refrigerator to expose the compressor and mechanical area. Remove the two screws on the retaining clamp of the compressor. Loosen two screws on the compressor base. Use a flat screwdriver to pry off the cover. Remove and replace the OLP and the PLC.

  • Page 59: Circuit Diagram (Block)

    LMX21981xx REFRIGERATOR CIRCUIT DIAGRAM LMX21981xx Page 57 TRAINING MANUAL...

  • Page 60: Test Mode

    LMX21981xx REFRIGERATOR 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 test button at main PCB controller. 3.

  • Page 61: Error Codes

    LMX21981xx REFRIGERATOR ERROR CODES LMX21981xx Page 59 TRAINING MANUAL...

  • Page 62: Error Code Er Rt

    LMX21981xx REFRIGERATOR ERROR CODE Er rt The error code Er rt will show on the display at the beginning of the test mode if there is a defective ambient sensor reading. Otherwise, it will not be seen by the customer and does not affect normal operation of the refrigerator.

  • Page 63: Pcb Function

    LMX21981xx REFRIGERATOR PCB FUNCTION 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 V ) and the MICOM and IC (5 V The voltage for each part is as follows: VA1 is a part for preventing over voltage and noise.

  • Page 64: Load Fan And Door Open Detection Circuit

    LMX21981xx REFRIGERATOR POWER CIRCUIT, continued LOAD FAN and DOOR OPEN DETECTION CIRCUIT LMX21981xx Page 62 TRAINING MANUAL...

  • Page 65: Open Door Detection Circuit Check

    LMX21981xx REFRIGERATOR OPEN DOOR DETECTION CIRCUIT CHECK LMX21981xx Page 63 TRAINING MANUAL...

  • Page 66: Refrigeration Compartment Stepping Motor Damper Circuit

    LMX21981xx REFRIGERATOR REFRIGERATION COMPARTMENT STEPPING MOTOR DAMPER CIRCUIT LED IN REFRIGERATOR / FREEZER (Optional) LMX21981xx Page 64 TRAINING MANUAL...

  • Page 67: Main Pwb (Layout)

    LMX21981xx REFRIGERATOR LED IN REFRIGERATOR / FREEZER (Optional), continued MAIN PWB ASSEMBLY LMX21981xx Page 65 TRAINING MANUAL...

  • Page 68: Dispenser Drive Pwb Assembly

    LMX21981xx REFRIGERATOR DISPENSER DRIVE PWB ASSEMBLY LMX21981xx Page 66 TRAINING MANUAL...

  • Page 69: Exploded Views

    LMX21981xx REFRIGERATOR EXPLODED VIEWS LMX21981xx Page 67 TRAINING MANUAL...
  • Page 70 LMX21981xx REFRIGERATOR EXPLODED VIEWS, continued LMX21981xx Page 68 TRAINING MANUAL...
  • Page 71 LMX21981xx REFRIGERATOR EXPLODED VIEWS, continued LMX21981xx Page 69 TRAINING MANUAL...
  • Page 72 LMX21981xx REFRIGERATOR EXPLODED VIEWS, continued LMX21981xx Page 70 TRAINING MANUAL...
  • Page 73 LMX21981xx REFRIGERATOR EXPLODED VIEWS, continued LMX21981xx Page 71 TRAINING MANUAL...
  • Page 74 LMX21981xx REFRIGERATOR EXPLODED VIEWS, continued LMX21981xx Page 72 TRAINING MANUAL...
  • Page 75 LMX21981xx REFRIGERATOR EXPLODED VIEWS, continued LMX21981xx Page 73 TRAINING MANUAL...

  • Page 76: Temperature Resistance Chart

    LMX21981xx REFRIGERATOR TEMPERATURE RESISTANCE CHART LMX21981xx Page 74 TRAINING MANUAL...
  • Page 78 Four Door Refrigerator - Fall 2008...

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