Welcome to the forums!
What year, brand and model of RV do you have?
Most RV fridges are designed to work on 120 volt (house power) and/or LP. On LP they still need 12v power to run the control board. In a few cases there are some RV fridges that use 12 volt power to run also, but they aren't that common anymore. If you know which model of fridge you have it would help us to trouble shoot.