More important than the generic owners manuals, I always make a list of every appliance, fridge, water heater, A/C, furnace, water pump, converter, etc. I then go on line and download AND PRINT the owners manual and the maintenance (repair) manuals. I keep them in a folder in my TT so that I have them available when (not IF) they are needed. I have used these a couple of times in my years of camping.
I have also used these manuals to trouble shoot furnace problems for other people with good results.