Samsung Air Conditioner Error Code E431

Error code E431 on a Samsung air conditioner indicates a self-diagnosis failure in oil balance valve 1, which is also referred to as the balance keeping valve. This component is part of the refrigerant and oil management system found in multi-split or VRF (Variable Refrigerant Flow) systems. Its function is to regulate the distribution of compressor oil across the system to prevent oil starvation at the compressor. When the system's self-check routine cannot confirm proper operation of this valve, whether due to a mechanical failure in opening or closing, or a problem with the associated temperature sensor, E431 is triggered.

The error specifically covers two failure categories: a mechanical breakdown of the valve itself (failing to open or close on command) and a sensor-related fault, including dislocation or defect of the oil valve 1 temperature sensor. The temperature sensor monitors conditions at the valve to confirm its operational state. If the sensor has shifted out of position or has failed electrically, the control board receives an invalid signal and flags the self-diagnosis as failed. This is why the first diagnostic step focuses on confirming the sensor is properly seated and making contact at its intended location.

Because this fault involves both mechanical and electronic possibilities, a systematic approach is required. A technician should begin by inspecting the sensor for physical dislocation before moving on to electrical testing of the sensor and wiring harness, and then evaluating the valve solenoid for proper actuation. Ignoring this fault can result in insufficient oil circulation, which puts the compressor at risk of serious damage over time.