This thermal switch, often mounted in the radiator, triggers the electric cooling fan to turn on when coolant temperature reaches a preset threshold, providing essential airflow when the vehicle is stationary or moving slowly. A failed switch can cause the fan to run continuously or not at all, leading to overheating. We supply accurately calibrated thermal switches. They provide a reliable on/off signal for the cooling fan circuit, ensuring the radiator receives auxiliary airflow exactly when needed to maintain a safe engine operating temperature, especially in traffic or hot climates.