Generally speaking, your RV refrigerator should be level for proper operation. This is because of how the fluid flows in the RV absorption fridge cooling system works. For proper liquid movement through the system, the fridge and, therefore, the RV cannot be significantly unlevel. However, there is some wiggle room, and your fridge doesn't need to be perfectly level for proper function, just mostly level. If you feel the camper levelness, that's probably a sign that it's unlevel for the fridge as well. If you feel good, the fridge should be fine. If your RV and fridge are too unlevel, you could experience degraded performance. If the liquid ammonia cannot flow smoothly through the fridge's fins, you will not get proper heat absorption.