The ornamental design for a wrench for an appliancefan, as shown and described.
FIG. 1 is a top view of the wrench for an appliance fan embodying my new design,
FIG. 2 is a bottom view thereof,
FIG. 3 is a front view thereof,
FIG. 4 is a rear view thereof,
FIG. 5 is a right side view thereof,
FIG. 6 is a left side view thereof,
FIG. 7 is a perspective side view thereof; and,
FIG. 8 is a bottom view of the wrench for an appliance fan engaged with an appliance fan, the appliance fan shown in phantom comprising no part of the present invention.