The ornamental design for a cap for aircompressor, as shown and described.
FIG. 1 is a front and upper perspective view of a cap for air compressor showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side elevational view thereof;
FIG. 7 is a right side elevational view thereof;
FIG. 8 is a rear perspective view thereof;
FIG. 9 is a front and bottom perspective view thereof;
FIG. 10 is a front and upper perspective view thereof, the openings and the ribs depicted by means of broken lines being for illustrative purposes only and forming no part of the claimed design; and,
FIG. 11 is a rear perspective view thereof, the openings depicted by means of broken lines being for illustrative purposes only and forming no part of the claimed design.