Samsung Air Conditioner Error Code YEL_ON_RED_FLICKER

The YEL_ON_RED_FLICKER error code on Samsung air conditioners indicates a discharge temperature sensor fault, specifically an open circuit or short circuit condition in the sensor circuit. The discharge temperature sensor monitors the refrigerant temperature as it exits the compressor. This measurement is critical for protecting the compressor from overheating and for regulating system performance. When the control board detects a resistance value outside the expected range at CN51 PIN#3 and PIN#4, it flags this fault and may shut down or limit system operation to prevent compressor damage.

An open circuit condition means the sensor circuit has been broken, causing the resistance reading to spike toward infinity. A short circuit means the sensor leads have made unintended contact with each other or with ground, causing resistance to drop toward zero. Both conditions produce readings the control board cannot interpret as valid temperature data. The sensor is a thermistor, meaning its resistance changes predictably with temperature, and any reading outside the designed range triggers this error.

Diagnosis begins at connector CN51 on the control board, specifically PIN#3 and PIN#4, where the discharge sensor wiring terminates. Using a multimeter, a technician can measure the resistance across the sensor leads and compare it to the temperature-resistance curve specified for this sensor type. A reading of zero ohms indicates a short, while an open line will show no continuity. Wiring harness condition, connector seating, and the sensor element itself should all be inspected as part of this diagnostic process.