The temperature sensor requires a control unit for the control system which is available in 12V (ILLZTC12-2K...) and 24V (ILLZTC24-2K...). The fan speed varies according to the actual oil temperature on the sensor. This reduces the noise level of the cooler system and increases the durability of the fan motor, because it is not running at maximum speed all the time. The start up temperature of this system is 44°C (111°F) and the maximum rotation of the fan is applied when the oil temperature reaches 55°C(131°F).