We claim the ornamental design for an end cap for a louver of a heater, as shown herein.
FIG. 1 is a perspective view of an end cap for a louver of a heater with the louver, a peg of the end cap, and cutouts of the end cap shown in broken lines that form no part of the claimed invention;
FIG. 2 is another perspective view of the end cap of FIG. 1 with a lock washer shown in broken lines that form no part of the claimed invention;
FIG. 3 is a front view of the end cap of FIG. 1 with the peg and cutouts shown in broken lines that form no part of the claimed invention;
FIG. 4 is a right side view of the end cap of FIG. 1 with the peg and the lock washer shown in broken lines that form no part of the claimed invention;
FIG. 5 is a rear view of the end cap of FIG. 1 with the lock washer and the cutouts shown in broken lines that form no part of the claimed invention;
FIG. 6 is a left side view of the end cap of FIG. 1 with the peg and the lock washer shown in broken lines that form no part of the claimed invention;
FIG. 7 is a top view of the end cap of FIG. 1; and,
FIG. 8 is a bottom view of the end cap of FIG. 1 with the peg and the lock washer shown in broken lines that form no part of the claimed invention.