My fridge (10 year old Elextrolux model PLHT219TCK0) is not cooling (60 degrees) while the freezer works fine. I thawed the freezer for 12 hours and when I turned it back on everything worked fine for a week and then the problem re-appeared. When I opened up the back of the freezer there is a build up of frost on all components. I am thinking that maybe the defroster is not working. See the attached pictures.
Usually there's a fan that moves air from the freezer to the fridge. It could be that the frost is preventing the fan from spinning and/or blocking the air chase between the two. Would probably take a week or so to build up to that point. If the defrosters not working, which, if that's the back of the interior of your freezer, it looks like it isn't, that's definitely what I would start checking.
I'm not fridge guy, but my first step would be to verify voltage to the defroster.