Wall in between the two sides was really hot, vacuumed out the fan and the wall cooled to normal temp. Next day we noticed that the freezer side was cold but not freezing anything. Refrigerator side seems fine. It's 12 years old so the question is... repair? Or replace?

It sounds like you still do not have it clean enough. You have to wash out the coils with soap and water, vacuuming them out does not remove greasey dirt that you have in a kitchen. Also, you could have a problem with the defrost system. Remove cover to coils in freezer and see if they are full of ice. If so, let me know and I will tell you what to do. If it is full of ice look at heater at bottom of coils and see if it's burned in two.