it is located in the bottom of the dehydrator,, so you take all your trays off and there is the fan in the middle,, it has a cover over it so food can't fall directly into the fan,, it is supposed to help circulate air better that way to dry food faster. Just have to make sure you don't have anything sitting close to your dehydrator when you have it on or it will get hot,, it needs a room around it so air can circulate
It is on the bottom, which is a poor design. It will get food in it, be hard to clean, and the unit will not last as long as one with the fan on the top or side.
The fan is located in the middle of the bottom of the machine. Then the trays stack on top of one another.