Welcome jeagle to irv2.
Take a look at
this thread it may give you an idea in this hot weather of what maybe needed.
Your owners manual should give you info on how to test your sensor on the fins within the box if there is a problem with that.
If you still have a problem let us know, a quick test for better venting to get heat from rear of fridge is place a 12v or 110 volt fan in your outside vent for quick cool down and see if things improve within box temps.
The freezers have always been cold its the box that gives the problem.