Samsung Air Conditioner Error Code OPERATION_TIMER_FLICKER

The OPERATION_TIMER_FLICKER error on a Samsung air conditioner indicates a fault in the indoor unit heat exchanger temperature sensor circuit. This sensor, commonly referred to as the pipe sensor or indoor coil thermistor, monitors refrigerant temperature at the indoor heat exchanger and provides feedback to the main control board for managing cooling and heating cycles. When the control board detects a reading outside the expected resistance range, it classifies the fault as either an open circuit (broken wire or failed sensor with infinite resistance) or a short circuit (shorted sensor or wiring with near-zero resistance), triggering this error and causing the operation and timer indicator lights to flicker.

The sensor itself is a negative temperature coefficient (NTC) thermistor, meaning its resistance decreases as temperature rises. A healthy sensor produces a predictable resistance curve at room temperature, and deviations from that curve signal a fault. The control board reads this signal through connector CN43 on the indoor unit PCB. Diagnostics should begin by unplugging the sensor connector at CN43 and measuring the sensor resistance directly with a multimeter. An open circuit will show infinite or very high resistance, while a shorted sensor will show resistance near zero ohms.

Common root causes include physical damage to the sensor wire harness from vibration or improper installation, corrosion at the CN43 connector pins, a failed thermistor element inside the sensor housing, or water intrusion into the connector. In some cases, the fault lies with the indoor PCB itself failing to correctly read an otherwise functional sensor signal. Addressing this error promptly is important because the unit cannot regulate refrigerant temperature accurately without reliable sensor input, which can lead to inefficient operation or protective shutdowns.