"220V Cooling Fan" operation with the changed conditions of heat, operate at a slower speed, DC fan will generate less noise and consume less energy. In most of the design requirements, the operating speed DC fan for several hours after the air temperature is usually lower than the maximum design temperature value. Secondly, the position sensors installed option should pay attention to the sensor in the proper position, try to make the sensor can be directly clamped surface to be cooled. "220V Cooling Fan" in operation, a temperature-controlled fan will run at a faster pace if the thermistor feel higher temperatures; and at lower temperatures, it will operate at low speed; in these more intermediate high and low fan speed is hardly due to temperature change. When "220V Cooling Fan" slow temperature changes, the fan speed changes are slow, will not suddenly change the fan speed and noise. The reaction time depends mainly on the length of its heat-sensing sensor sensitivity.