The temperature is fluctuating between 0 for freezer and 37 for fridge to up to 40 for freezer and 52 for fridge. What's up?
You will want to check the thermistors to make sure that they fall with in specs. The thermistors should have a resistance value as follows. At 0 degrees resistance should be 42.2K ohms, at 37 degrees resistance should be 14.4K ohms and at room temp 77 degrees should be 5K ohms. If the resistance is not correct then replace the thermistors. If this checks ok then the issue will most likely be caused by a control board if the fans stop running and compressor stops running. If the fans and compressor and continuing to run then it sounds like a restriction in the sealed system causing the issue.