FIG. 1 is a front, bottom, and right side perspective view of an air conditioner showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a top plan view thereof;
FIG. 4 is a bottom plan view thereof;
FIG. 5 is a left side elevational view thereof;
FIG. 6 is a right side elevational view thereof;
FIG. 7 is a rear elevational view thereof; and,
FIG. 8 is an enlarged vertical cross-sectional view thereof taken along line 8-8 in FIG. 2, with the broken-line disclosure understood to show internal elements which are part of the article in which the claimed design is embodied, but which form no part of the claimed design.