Is this RV new to you? Did the refrigerator work properly before now or has this become a problem recently?
Is the problem frost building up on the refrigerator compartment fins, or is the problem the refrigerator is too cold and is freezing the food?
Not knowing your experience, I'll suggest the following. Pardon me if you already know this.
If the fins are getting covered by frost, you may be having a normal condition. The refrigerator is not self-defrosting. Unless the refrigerator compartment is staying below freezing, the frost on the fins should melt off in an hour or so if you turn it off. The cooling system keeps the fins below freezing to cool the compartment, but when it's off for a while the compartment temperature will defrost the fins. When we are on the road, I have to defrost the freezing compartment about once per month.
You may have already tried this, but if it is freezing the food, but be sure the thermistor is on the fin that it closest to the right side. That fin gets the most accurate temperature reading. Slide it down to reduce the cooling amount (increase the refrigerator temperature).
You can search this forum with the phrase refrigerator freezing and find several threads about it. Here's one:
Refrigerator has one setting - Freezing (Solved)