Welcome!
Sorry there is no owners manua other than some printed up stuff like how to level the trailer and generic things like that. The only things my previous new trailers came with were the manuals for all the appliances and anything the manuf buys from outside sources. The light switch sounds like an add on by a previous owner. Neither my 05 Cherokee or my 07 has a house type switch. That will be a task to figure it out.
As far as the A/C, my best guess is that it is low or empty on refrigerant. They are a sealed system with no provision for recharging. However a good A/C guy can splice in a charger port and inspect for a leak and hen recharge it after fixing it. My neighbor who does commercial A/C did this for my old Award TT and it worked perfect after that.
As far as the AC you should be able to go to the manuf website and download a owners manual and install manual.
Good luck with the new trailer.
Wife Kim
Son Brandon 17yrs
Daughter Marissa 16yrs
Dog Bailey
12 Forest River Georgetown 350TS Hellwig sway bars, BlueOx TrueCenter stabilizer
13 Ford Explorer Roadmaster Stowmaster 5000, VIP Tow>
A bad day camping is
better than a good day at work!