I claim, the ornamental design for a fixing plate for an upper cover of an air compressor, as shown and described.
FIG. 1 is a perspective view of a fixing plate for an upper cover of an air compressor showing my present design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left view thereof;
FIG. 5 is a right view thereof;
FIG. 6 is a top plan view thereof,
FIG. 7 is a bottom plan view thereof. The broken lines in FIG. 7 are included for the purpose of illustrating a portion of the fixing plate for an upper cover of an air compressor and forms no part of the claimed design; and,
FIG. 8 is a perspective view showing the present design in use.
The broken lines shown in FIG. 8 are for illustrative purposes only and form no part of the claimed design.