'89 Park Ave. a/c clutch not engaging

My mom's a/c quit working today, the compressor clutch isn't pulling in. Checked the fuse labeled "a/c cluster", fuse #5A but it was good. The fuse panel diagram shows fuse #5D as "base A/C" but that fuse slot is empty. I metered the connector at the clutch and no voltage there. Tried a spare fuse in the 5D slot to no avail. The next stop is GM service dept. if I don't get help here. Any suggestion would be greatly appreciated. TIA, buck

Check your freon level? Should be an R-12 system, have fun spending lots to get that fixed...

Doesn't sound very encouraging but thanks for the help.