Kitchenaid KSSC48QKS02 fridge side is too cold?

had a problem with yet another kitchenaid product, this time our side by side refer. At first, the fridge side was way too warm, 56 to 63 degrees. It had the diffuser replaced about a year ago. I shut the refer off for a day and then restarted it. Now, even with the thermostat set at 34 degrees, the refer temperature is 27 degrees. May cycle up to 41 degrees but goes immediately back to 27. Freezer stays at 0 degrees which was bumped up from -9 degrees. Is the thermistor going bad? Help