I am having the same problem with my GE Monogram side-by-side. It too, is about 14 years old and over-cooling in the refrigerator. I tried installing two new thermistors (there was an upper and a lower one on the fridge side), but that did not solve the problem. I have it set to 42 degrees (digital), and this morning, the fridge was at 33 degrees. Also, when I wired in the new thermistors, I could not see any markings on the wires coming from the fridge. I assume that means you cannot wire them incorrectly? Maybe the thermostat?