Go thru the RV and locate the ID tags for every different appliance and take pictures of the data tags. Water heater, open the outside door. Stove, push hard on the top and lift the front, to disengage the top, data tag is under there. Fridge, remove the outside access door to find the data tag. A/C is not easy, usually its inside the plenum and you have to remove the inside trim or filter, some are on the outside and you have to get on the roof and remove the cover to find them. Furnace tags, I'm not sure, probably remove the outside access and look in there first.
Knowing the exact model number you can do some searching for the owners manuals, installation manual (usually combined with the owners manual) and possibly service manuals. Here is a good list of places to look.
RV tech, service and owners manual sources.
Technical Service Manuals – PDX RV
Bryant R.V. Services
Index of /pdf (scroll down to Atwood and Suburban)
Service Manuals - My RV Works
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rvrepairguru.com
Free RV Manuals
Component Manuals Search | Forest River Inc., A Berkshire Hathaway Company (even if not a Forest River, they may have the manual you need)
Prime Time has partnered with top component manufacturers. Use this search to find manuals for your RV.
primetimerv.com
Service/User manual Downloads – RV Refrigerator Repair
Your RV Refrigerator boiler operates at about 350 degrees all the time, but even a brief time off-level, like driving up a hill, can send that temperature sky-rocketing. Events like this produced a lot of thermal stress in the fridge boiler, stress that causes the metal to fatigue and the...
www.arprv.com
Charles