Unplug the thermistor. That will put the fridge full on and if it gets cold, replace the thermistor. If it doesn't get any colder, your cooling unit maybe shot. Thermistor should be part of the light harness on that model.
I assume you checked the temp setting and tried adjusting that? I think mine is on 6.
2017 Eagle 293RKDS, factory ordered, lots of mods and upgrades. More than I can list.
2018 Ram 3500 crew cab long bed SRW diesel 6spd Aisin 4wd Tradesman.
B&W Ram puck 5th wheel
Mopar wheel to wheel steps