well, your dealer should have covered that, during your PDI.
3-way fridges are generally only found in truck campers and popups(and similar smaller trailers)because they are much smaller than 2-way fridges, which would exhaust a tow vehicle's battery trying to cool it down.
nearly all travel trailers, 5th wheels and motorhomes have 2-way fridges. and most of us run it on propane while traveling.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC