LG Refrigerator Error Code LED 1 blink

The LED 1 blink error on an LG refrigerator indicates a Compressor AD Offset Error, specifically designated as an FCT0 error. This fault is detected during the compressor off state and relates to a malfunction in the analog-to-digital conversion circuitry responsible for reading motor voltage and current sensor signals. The main control board continuously monitors these sensor values even when the compressor is not running, and if the offset readings fall outside acceptable calibration thresholds, the board flags this as a sensor error rather than a true compressor fault.

This error is rooted in the main PCB's internal sensing and signal processing circuitry. The AD offset refers to the baseline zero-point calibration of the current and voltage sensing inputs. When the compressor is off, those inputs should read at a known reference level. If the board detects a deviation from that reference, it cannot trust future compressor operating data and triggers the FCT0 fault to prevent potential damage from running the compressor under unmonitored conditions.

The most common cause is a fault within the main control board itself, either due to a failed sensing component, corrupted firmware calibration, or internal circuit degradation. Because this error is detected before the compressor even starts, external wiring issues or compressor hardware problems are less likely culprits. A power reset can sometimes clear transient signal glitches that mimic this fault, but if the error returns after resetting, the main board requires replacement.