I have the same frig and it would not keep ice cream frozen, always very soft no matter the position of the thermistor. I added a 100,000 ohm resistor across the thermistor leads inside the control box (outside access) to drop the temps in the freezer & fridge a few degrees. (I found the thermistor lead a bit short too so that it would show or hide when sliding the inside adjuster.) My older Dometics all controlled better but there is no adjustment on the controller board. You would have to replace it with a Dinosaur board to get better calibration.
