Samsung Air Conditioner Error Code 311

Samsung air conditioner error code 311 indicates a fault in the liquid pipe temperature sensor circuit, specifically on a double-pipe refrigerant line configuration. This sensor monitors the temperature of the liquid refrigerant line and provides critical feedback to the control board for managing refrigerant flow, preventing flooding, and optimizing system efficiency. When the control board detects a signal outside the expected resistance range, either an open circuit or a short circuit condition, it triggers error code 311 and halts normal operation to prevent potential system damage.

The three root causes identified for this fault are connector dislocation, wire breakage, and a defective sensor itself. Connector dislocation occurs when the sensor harness plug becomes loose or partially unseated from the control board or sensor terminal, interrupting the signal. Wire breakage typically results from physical damage such as pinching, corrosion, or fatigue cracking along the sensor harness. A defective sensor means the thermistor element inside the sensor has failed internally, producing resistance values outside the acceptable operating range.

Diagnosis should begin by visually inspecting the liquid pipe temperature sensor wiring harness for any visible breaks, chafing, or loose connections. The sensor connector should be firmly reseated and the circuit tested with a multimeter to confirm continuity and verify sensor resistance values fall within the specification expected by the control board. If the wiring and connections check out, the sensor itself should be tested and replaced if it reads open, shorted, or out of range.