Auto Wick Dry automatically runs when the water level in the tank is very low to empty, this feature helps to dry the wick fully between uses, preventing mold or mildew buildup. In the factory default setting, the auto wick dry function runs on fan speed 1 for 8 hours to dry the wick out, this can be adjusted by pressing and holding the fan speed button for 15 seconds to change to a faster wick dry cycle that runs fan speed 3 for just 2 hours to accomplish the same level of wick drying.