The ornamental design for the air conditioner, as shown and described.
FIG. 1 is a perspective view of the front, right and top sides of an air conditioner showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a right side view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof; and,
FIG. 7 is perspective view shown in a position of use thereof.
The broken line showing of the air conditioner is included for the purpose of illustrating portions of the air conditioner and forms no part of the claimed design.