LG LMXS30776S Service Manual

The LG LMXS30776S is a 30-inch French Door Refrigerator with Smart Cooling Plus™ technology, Door Cooling+™, SmartThinQ® connectivity, InstaView™ Door-in-Door®, Craft Ice™ maker, and linear compressor. This service manual provides detailed information for qualified technicians regarding safety procedures, technical specifications, component locations, disassembly/assembly instructions, diagnostic codes, troubleshooting, and wiring diagrams.

1. Safety Precautions 2. Product Specifications 3. Component Locations & Exploded Views 4. Disassembly & Reassembly Procedures 5. Electrical Data & Wiring Diagrams 6. Refrigeration System 7. Control System & Diagnostics 8. Error Code Diagnostics 9. Test Mode Procedures 10. Troubleshooting Flowcharts 11. Parts List & Exploded View Reference

Safety Precautions

Before servicing, disconnect power. Use proper tools and follow ESD precautions.

Hazard	Precaution
Electrical Shock	Unplug unit before accessing internal components. Verify capacitor discharge.
Refrigerant	Use certified recovery equipment. Avoid open flames. Ventilate area.
Sharp Edges	Wear cut-resistant gloves when handling evaporator, condenser, or sheet metal.
Heavy Parts	Use assistance when lifting compressor, doors, or cabinet.
ESD Damage	Use grounded wrist strap when handling PCBs (Main Control, Display).

Product Specifications

Model: LMXS30776S
Type: 30 cu. ft. French Door Refrigerator with InstaView
Electrical: 115 VAC, 60 Hz, 7.5 A (rated)
Refrigerant: R-600a (Isobutane) - 2.5 oz
Insulation: Cyclopentane in foam
Compressor: Linear Compressor (LBP type)
Defrost System: Adaptive defrost with heater (400W)
Dimensions (HxWxD): 69.875" x 35.75" x 34.5"
Net Weight: 326 lbs
Smart Features: SmartThinQ® (Wi-Fi), InstaView™, Door Cooling+™, Craft Ice™

Component Locations & Exploded Views

Key component locations: Main PCB (rear top), Display PCB (door), Inverter PCB (compressor area), Temperature Sensors (fresh food/ freezer evaporator, duct, room), Damper Motor, Ice Maker Assembly, Water Valve, Evaporator Fan Motor, Condenser Fan Motor.

Exploded Views: Door assembly, liner, shelf and drawer assemblies, mechanical compartment, dispenser assembly.

Disassembly & Reassembly Procedures

Door Removal: Remove hinge covers, disconnect wiring harnesses, support door, remove hinge bolts.
Main Control PCB Access: Remove rear service panel, disconnect connectors, note positions.
Evaporator Cover Removal: Remove rear panel in freezer, disconnect fan and heater connectors.
Water Filter Housing: Turn filter to unlock, pull out. Release tabs to remove housing if needed.
Dispenser Control Panel: Remove screws behind kickplate, gently pry control panel from door.

NOTE: Take photos during disassembly. Label all connectors and screws.

Electrical Data & Wiring Diagrams

Refer to wiring diagram sheet (included in manual pack).

Main PCB Connector Pinouts: CN201: Power Input (L, N, G). CN701: Display & Touch Panel. CN301: Compressor Inverter. CN401: Damper Motor, Fan Motors. CN501: Temperature Sensors (Thermistors).

Resistance Values (at 77°F): Room Temp Sensor: 10 kΩ. Evaporator Sensor: 10 kΩ. Freezer Sensor: 10 kΩ.

Refrigeration System

Sealed system with linear compressor, capillary tube, evaporator, condenser.

Compressor: LBP type, 3-pin connector (U, V, W).
Evaporator: Freezer section, aluminum fin-and-tube.
Condenser: Wire-on-tube, located at rear bottom.
Filter Drier: Located near compressor.
Service Ports: Process tube on filter drier (low side), compressor discharge (high side).

Charging: Weigh-in method only. Required charge: 2.5 oz R-600a.

Control System & Diagnostics

Main Control Board monitors sensors, controls compressor speed, damper, fans, defrost. Enter diagnostic mode by pressing "Freezer" and "Ice Type" buttons simultaneously for 3 seconds (on dispenser panel).

Display Codes: Shows sensor temperatures, error history, component test modes.

Error Code Diagnostics

Error Code	Description	Probable Cause
ER-IF	Inverter Fault	Compressor/Inverter PCB failure, wiring.
ER-FF	Freezer Fan Fault	Fan motor blocked, connector, motor failure.
ER-RF	Fresh Food Fan Fault	Fan motor blocked, connector, motor failure.
ER-DS	Door Switch Error	Switch stuck, wiring, main PCB.
ER-CF	Communication Failure	Wiring between Main PCB and Display PCB.
ER-TH	Thermistor Error	Open/short circuit in sensor, connector.

Test Mode Procedures

In Diagnostic Mode, use buttons to select test functions.

Forced Defrost Test: Activates defrost heater for 2 minutes.
Compressor Run Test: Runs compressor at fixed speed.
Fan Motor Test: Runs evaporator and condenser fans.
Damper Motor Test: Opens/closes fresh food damper.
Ice Maker Test: Cycles ice maker through harvest sequence.
Dispenser Switch Test: Tests water and ice dispenser switches.

Exit: Press and hold "Power Freeze" and "Power Cool" for 3 seconds.

Troubleshooting Flowcharts

Follow systematic approach: Verify power, check error codes, inspect components, perform tests.

No Cooling: Check compressor operation, fans, sensors, refrigerant charge.

Excessive Frost: Check door seal, defrost heater, thermostat, defrost sensor.

Water Leak: Check drain tube (clogged), water valve, water line connections, ice maker assembly.

Dispenser Not Working: Check water supply, filter, valve, switch, control board.

Display Blank: Check power to main/display PCB, wiring harness, door switch.

Parts List & Exploded View Reference

Key replacement parts (LG part numbers):

Main Control PCB: 6325ER1003A
Display PCB (InstaView): 6871ER2005B
Linear Compressor Assembly: 383JER1001A
Evaporator Fan Motor: 4430ER1001A
Damper Motor: 3870ER1002A
Ice Maker Assembly (Craft Ice): 6380ER4002B
Water Valve Assembly: 3855ER1001A
Temperature Sensor (10kΩ): 6750ER1001A
Door Gasket (Freezer): MDS62462301

Ordering: Use full model number (LMXS30776S) and serial number for precise parts.