With "Waterproof Cooling Fan" application and ambient temperature changes, and sometimes require different speed fan to meet demand. Some manufacturers specially designed adjustable fan speed cooling fan, manual and automatic modes. "Waterproof Cooling Fan" is primarily so that users can use a low speed in the winter to get low noise, high speed to get good cooling effect in the summer. Automatic class radiator thermostat with a temperature sensor in general, according to the current working temperature control fan speed, "Waterproof Cooling Fan" high temperature will increase speed, low temperature, then reduce speed to achieve a dynamic balance , so that the cooling effect of wind noise and maintain an optimal combination of points.