I have a GE side by side refrigerator that has been quitting.
Frost forms on inside back wall of freezer then the fridge side starts warming up then the water dispenser stops working. I have defrosted the freezer manually and cleaned all dust from the back. How can I fix it?

Are you keeping the controls in the mid range?
If you have them up in the high colder range it will freeze the freon making it act like it is not working.

No, I have controls set mid-range

Mine does the same thing. I use a hair dryer every 2 weeks to defrost the back of my freezer. I have the control for the freezer on 1 and the one in the icebox on midrange. It works fine for about 2 weeks then freezes up. Someone said a fan was out underneath the icebox. I have never seen any fan control on the bottom.