FIG. 1 is a front perspective view of a fan showing the new design;

FIG. 2 is a front side elevation view thereof;

FIG. 3 is a top side elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof; and,

FIG. 6 is a rear side elevation view thereof.

The bottom view forms no part of the claimed design. The broken line showing of environmental structure in FIGS. 1-6 is for illustrative purposes only and forms no part of the claimed design.