Unfortunately most RV owner's manuals are pretty useless. They are generic in nature to cover all legal liability issues and little else. If you hope to get details of where the fuse panel is and what each circuit covers, it's usually not there. You might learn a lot of information by looking at manuals for other RVs. Winnebago has a pretty complete set and their manuals available for download and are better than most.
You might also look here:
Manuals - 1989 & older - RVing-The Midwest Connection
Since most systems and appliances are made by only a few manufacturers, Write down the make and model of each component in your RV. Then you can search on line for manuals, troubleshooting guides, and parts lists. You can start here:
Service Documents and Manuals
Your Class C is probably on a Ford E350 chassis. A quick Google search shows numerous sources of repair guides for the chassis.
1990 Ford E-250 Econoline Repair Manual Online
Ford E350 Econoline Repair Manual - Service Manual - Chilton Haynes - 1994 1995 1990 1986 1987 1989 1993 1984 94 95 90 86 87 89 93 84 - PartsGeek.com
Ford Econoline E-350 Repair Manual from Haynes
Good luck. Once you find the manuals you'll have lots to read!