Aside from a defective thermistor, I've always had trouble with the rv fridges freezing up on the higher settings (eggs, yogurt, milk), especially when camping in hotter climates than Ohio.
Improved airflow around the food always works for me.
You can buy a fridge fan that runs on D batteries for under 20 bucks. I have two. The batteries last a really long time for us using a good name brand alkaline.
Here's a link for a couple on Amazon. I have the $15 Camco and it works fine.
Valterra A10-2606 FridgeCool 11.28 mA Fan with On/Off Switch
Camco 44123 Fridge Airator