LG Dishwasher LDF7551ST Service Manual

The LG LDF7551ST is a built-in dishwasher featuring QuadWash™ technology with multi-motion arms, TrueSteam® for sanitization, LoDecibel™ quiet operation, SmartThinQ® technology for Wi-Fi connectivity, EasyRack™ Plus adjustable upper rack, Stainless Steel tub, 6 wash cycles including Heavy, Normal, Light, Rinse Only, Express, and Sanitary cycles, with LED display and hidden controls. Below are key sections for safety, features, installation, operation, maintenance, and troubleshooting.

1. Features at a Glance 2. Installation 3. First-Time Setup 4. Specifications 5. Controls and Settings 6. Connecting to Utilities 7. Operating Cycles 8. Maintenance & Cleaning 9. Regulatory Information 10. Troubleshooting

Features at a Glance

Key components: QuadWash™ system, TrueSteam® sanitization, SmartThinQ® connectivity, EasyRack™ Plus adjustable racks, Stainless Steel interior, LED display with hidden controls.

Feature	Description
QuadWash™ Technology	Four multi-motion arms for thorough cleaning
TrueSteam®	Steam sanitization cycle for hygiene
SmartThinQ®	Wi-Fi connectivity for remote control
EasyRack™ Plus	Adjustable upper rack with fold-down tines
LoDecibel™ Operation	Quiet performance at 44 dBA
Stainless Steel Tub	Durable and resistant to stains
LED Display	Hidden touch controls with status indicators
6 Wash Cycles	Heavy, Normal, Light, Rinse, Express, Sanitary
Water Heater	Built-in heating element
Soil Sensor	Automatically adjusts cycle based on soil level

Installation

Unpack and inspect contents. Ensure proper electrical and plumbing connections.

Electrical connection: Requires 120V, 60Hz dedicated circuit; connect to grounded outlet.
Water supply: Connect to hot water line (120°F recommended) with water supply line.
Drain connection: Connect drain hose to sink drain or garbage disposal.
Leveling: Adjust leveling legs to ensure unit is stable and level.
Final check: Secure all connections and test for leaks.

WARNING! Disconnect power before installation. Ensure proper grounding to prevent electrical shock.

First-Time Setup

Power on dishwasher; follow initial setup procedure.

Remove shipping materials: Take out all tape and protective coverings.
Load detergent: Fill main detergent dispenser; use rinse aid if desired.
Select language: Set display language through control panel.
Test run: Run a quick rinse cycle to check operation.
Connect SmartThinQ: Download app and connect to Wi-Fi for remote features.

CAUTION! Do not operate without water supply connected. Ensure drain hose is not kinked.

Specifications

Model: LDF7551ST
Type: Built-in Dishwasher
Capacity: 14 place settings
Noise Level: 44 dBA
Wash Cycles: 6 main cycles + options
Water Connection: Hot water required (120°F)
Electrical: 120V, 60Hz, 15A
Dimensions: 33.875"H x 23.875"W x 24.5"D
Weight: 105 lbs
Warranty: 10-year limited on tub

Controls and Settings

Access controls via hidden LED display. Press area above display to reveal controls.

Cycle Selection: HEAVY, NORMAL, LIGHT, RINSE, EXPRESS, SANITARY

Options: HEATED DRY, DELAY START, SABBATH MODE, CHILD LOCK

SmartThinQ Settings: Remote start/stop, cycle monitoring, diagnostics

Display Indicators: Cycle progress, time remaining, error codes

Connecting to Utilities

Proper utility connections are essential for optimal performance.

Water Supply: Connect to hot water line (120°F recommended).
Drain: Connect to sink drain or garbage disposal with air gap.
Electrical: Dedicated 120V, 15A circuit with proper grounding.
Ventilation: Ensure adequate space around unit for air circulation.

Tip: Use only copper or braided stainless steel water lines. Avoid plastic drain lines that can kink.

Operating Cycles

Select appropriate cycle based on load and soil level.

Heavy: For heavily soiled pots and pans
Normal: Everyday dishes with normal soil
Light: Lightly soiled dishes, quick wash
Rinse Only: Rinse without detergent
Express: 30-minute quick wash
Sanitary: High-temperature wash with steam
Options: Heated Dry, Delay Start (1-24 hours)

WARNING! Load dishes properly to ensure water spray reaches all surfaces. Do not overload.

Maintenance & Cleaning

Regular maintenance ensures optimal performance and longevity.

Filter cleaning: Remove and clean filter monthly
Spray arms: Check for clogs and clean as needed
Door seal: Wipe clean to prevent leaks
Interior: Run cleaning cycle with dishwasher cleaner
Exterior: Clean with mild detergent and soft cloth

CAUTION! Unplug unit before cleaning. Do not use abrasive cleaners on stainless steel.

Regulatory Information

UL listed; complies with NSF/ANSI 184 for residential dishwashers. Energy Star® certified. Manufactured by LG Electronics. For support, visit www.lg.com or contact 1-800-243-0000. Serial number located on door frame.

Troubleshooting

Symptom	Possible Cause	Corrective Action
Dishwasher won't start	Power/child lock	Check power supply; ensure child lock is off; close door completely.
Poor cleaning	Spray arm/filter	Clean filter; check spray arms for obstructions; use proper detergent.
Water not draining	Drain hose/kink	Check drain hose for kinks; ensure proper drain connection.
Leaking water	Door seal/detergent	Check door seal; ensure proper detergent amount; level unit.
Error codes displayed	Various issues	Refer to error code chart in manual; reset unit if needed.

Reset: Unplug for 1 minute or press POWER for 10 seconds.

Service: 1-800-243-0000; www.lg.com