If you can not find a model specific Owner's manual, which as Tom said is not really worth much. There are two books you might find useful.. Pick one (You don't need both)
The RV Book
The RV Owner's Handbook
Most Better RV places including Camping world will have one or the other, One is published by a division of the company that owns Camping World so they always have it in stock.
I have found that some chapters were better than the Factory Manuals.. These books are written by RVers for RVers.
And in addition, every "Device" right down to doors and mirrors and such have owner's manuals.. If you can identify the make and model.. you google replacing the words MAKE and MODEL with the make and model number
Google: Make, Model, Manual
Example Carrier AIR V Manual (the factory original air conditioners on my RV)
Often this will take you direct to a link to download the PDF of the owner's manual
Or it will at least get you to Carrier's corporate web page and from there Support and Manuals,, the path may vary... NOTE: I do not recommend Carrier air conditioners. Had to replace both of mine due to a DESIGN fault.