LG bottom-freezer (single fresh-food door) refrigerator: field service manual

Covers: LG bottom-mount refrigerators with one fresh-food door and a freezer drawer (LDCS, LDNS, LBNC and similar series), electronic controls with alphanumeric error codes. Many use LG's inverter or linear compressor.

Single sourceBrands: LG8 components

A single-evaporator LG with the freezer below and an electronic main board. The board monitors its fans and sensors and shows codes such as FF, dH, rS and CO. That makes diagnosis faster than on a mechanical top-mount, but a code points to a circuit, not a part. Fresh-food air comes up from the freezer coil through a motorized damper.

Safety first

Unplug the unit before service.
Live checks at the main board or inverter drive are caution work.
Codes CH/CL and any compressor or refrigerant work are blocked: refer to an EPA 608-certified technician.

How it works

The evaporator and freezer fan are behind the freezer drawer's rear wall. Cold air goes into the freezer and up a duct to the fresh-food section through a damper the board opens and closes based on the fresh-food sensor. The compressor, condenser and condenser fan are at the bottom rear.

The board reads thermistors for the fresh food (R1, and R2 on some models), the freezer, the defrost (evaporator) and room temperature. LG lists separate codes for each: rS, r2, FS, dS and rT.

Defrost: a heater on the evaporator is protected by a thermal fuse (LG calls it a temperature fuse). LG sets code dH when the defrost sensor fails to warm by more than 5°C within about 80 minutes of a defrost start. LG lists a broken heater or fuse, a heater relay problem or a clogged drain as causes.

LG notes that codes may be prefixed E, r or Er, and that you can make the display show a stored code (for example after a power failure) by holding Freezer Temperature and Express Freeze together for at least 3 seconds on models with those keys.

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.

Diagnostic guides for this appliance

Guide · Refrigerator

Adaptive defrost control (ADC) board: how to diagnose it

An adaptive defrost board replaces the old cam timer. It counts compressor run time (and on some boards door-open time) and adjusts the next defrost interval based on how long the last one took. Test the heater and the cold bimetal first, then force a defrost: if the heater warms on a forced defrost but the coil still ices, the board isn't starting defrost on its own.

8 steps ~60 minmoderate

Guide · Refrigerator

Ice dispenser not dispensing ice (ice maker is making ice)

Most cases are mechanical: cubes fused into a block, a bin not fully seated on the auger drive, or ice behind the auger motor. After that, check the electrical path: door switch, dispenser switch, auger motor voltage and, on crushed/cubed models, the cube solenoid. Water dispensing working is a useful clue that the dispenser control has power.

8 steps ~45 minmoderate

Guide · Refrigerator

Refrigerator runs all the time

First decide if it's really a problem. Whirlpool says 40-80% run time is normal at average room temperature, and newer variable-speed compressors are designed to run long at low speed. If it's truly excessive, the usual causes are heat-rejection problems (dirty condenser, dead condenser fan), air leaks (gaskets, doors) and a frosted evaporator. A compressor or refrigerant fault is a referral.

8 steps ~45 mineasy

Other refrigerators manuals

Manual · Refrigerator

Whirlpool / Maytag / Amana top-freezer refrigerator (WRT series): field service manual

Whirlpool-built top-mount refrigerators sold under the WRT and similar series and their sister badges: older units with a mechanical defrost timer, and later units with an adaptive defrost control (ADC) board. Dial or slider controls, single evaporator in the freezer.

9 components6 common failuresWhirlpool, Maytag, Amana, Roper

Manual · Refrigerator

GE / Hotpoint top-freezer refrigerator (GTS, GTE, GIE series): field service manual

GE-built top-mount refrigerators in the GTS, GTE and similar series and Hotpoint equivalents: older units with a mechanical defrost timer, later units with an electronic defrost control board. Two-dial controls (freezer and fresh food) or a single cold-to-coldest dial.

8 components5 common failuresGE, Hotpoint

Manual · Refrigerator

Frigidaire top-freezer refrigerator (FFTR, FFHT, LFTR series): field service manual

Frigidaire-built top-mount refrigerators in the FFTR, FFHT and similar series, with a mechanical cold control and air-damper control, or slider/electronic controls on some models. Single evaporator in the freezer. Mechanical timer on older units; adaptive defrost control on many later ones.

7 components5 common failuresFrigidaire, Electrolux-built