Samsung Air Conditioner Error Code E103

The E103 error code on a Samsung air conditioner indicates a fault with the EVAP OUT sensor, also called the heat exchanger outlet sensor or evaporator outlet thermistor. This sensor is mounted at the outlet side of the indoor evaporator coil and monitors refrigerant or coil temperature as it exits the heat exchanger. The PCB uses this temperature data to regulate compressor operation, prevent freezing, and optimize cooling efficiency. When the control board detects a resistance reading outside the expected range, it classifies the fault as either an open circuit (infinite resistance, indicating a broken wire or failed sensor) or a short circuit (near-zero resistance, indicating an internal sensor failure or wiring short).

The most common trigger for E103 is a physical disconnection of the sensor connector from the indoor PCB. Vibration, handling during filter cleaning, or an improperly seated connector during a prior service call can cause the plug to work loose. Beyond connector issues, the thermistor itself can fail internally, producing a resistance value that falls outside the acceptable operating window. Wiring harness damage from rodents, pinching, or heat exposure can also create an open or short condition along the signal wire between the sensor and board.

Diagnosing E103 begins with inspecting the sensor connector at the PCB for secure seating and corrosion on the terminals. With the unit powered down, measuring resistance across the sensor terminals confirms whether the thermistor is within specification or has drifted to an open or shorted state. A healthy NTC thermistor will show a measurable, finite resistance that changes with temperature. A reading of infinite resistance confirms an open circuit, while a reading near zero ohms confirms a short.