Welcome to iRV2. The electronic part of the frig controls work from the 12 VDC (volt DC) side. The electric heater is rated for 120 VAC. IS the frig a Dometic or a Norcold?
Do you have the manuals on the frig? If not they are available online from the manufacturers. Just Google the brand and model+manual.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot