Hi, my name is Peter.
This refrigerator has a mechanical temperature control in the refrigerator section a the top. The sensor sits behind the control section by the air inlet ports from the freezer. The most common temperature variation cause is tall or large amounts of food restricting air flow coming into the refrigerator and not allowing proper air flow to circulate.
What can also cause this issue is a very small amount of food in the freezer which can cause extremely cold air to enter the refrigerator section. This is caused by not enough load is the freezer. If that is the case fill up a couple of gallon milk jugs 2/3 full and put them in the freezer.
Also I have seen if there is only 1 or 2 people in the household and the refrigerator is not opened frequently it will not run often enough and that will cause the cold air to settle at the rear and bottom of refrigerator causing freezing condiitions. To solve this issue you have to actually turn the refrigator colder so that is will run more often.
If I may help further please send the question directly to me.
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