"Micro Cooling Fan" With the application and ambient temperature changes, sometimes requires a different fan speed to meet demand. Some vendors specially designed adjustable fan speed cooling fan, manual and automatic modes. Manual is designed to allow users to use low speed to obtain low noise in the winter, summer use high speed "Micro Cooling Fan" to get a good heat dissipation. Automatic class thermostat radiator thermostat generally has a sensor that automatically controls the fan speed based on the current temperature, the temperature is increased by high speed, low temperature, then reduce speed to achieve a dynamic balance, so that the "Micro Cooling Fan"wind noise and heat dissipation to maintain an optimal combination of points.