Air conditioner

FIG. 1 is a perspective view of an air conditioner embodying the inventive ornamental design;

FIG. 2 is a front view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof.

The rear view of the air conditioner is omitted as it does not include any claimed features. The broken lines illustrate unclaimed features that form no part of the claimed design.