Welcome to the world of crappy RV refrigerators. They're all bad, just some worse than others.
. And unfortunately they work as designed.
Depending on the age of the
refrigerator, it will work better when the frig is near-perfect level. Put a bubble level on the bottom of the frig and level the trailer to that.
Do NOT overpack the refrigerator! All product inside needs airspace. Put items in the
refrigerator as you buy it. Diary and protein needs to be kept cold. Fruits/vegetables need to be kept cool... put these in a cooler with blue ice (or the like) if it keeps your
refrigerator from being stuffed. The freezer on the other hand works better if it's
full. Even if being full means blue ice, water bottles, etc.
I always carry 3-4 half-gallon milk jugs filled with water that I put in the freezer. I start out with one of these in the frig next to the
cube fan. It helps to lower the temperature (faster) and assists in general cooling. I rotate the milk jugs as needed.
AND... if you can park where the refrigerator side of the trailer is mostly kept in the shade... all the better.
Best of luck!