RF18HFENBSR. The refridgerator back panel has fins to cool the fridge. There is a drain for condensation to drain out. The entire back panel has frozen causing the water drain to plug. The fridge was purchased in November 2015. It froze December 2016 1 month after the warranty expired. I had it repaired, they replaced the warming metal with a longer one to penetrate deeper into the water drain to prevent freezing. The fridge worked fine until july 2019, then it froze again.
It's recommended to do the following tests before contacting Samsung to arrange a repair.
If your freezer door gasket is damaged, worn or is pulling up in place, warm air and moisture could be entering the freezer. This situation can be greatly amplified if you live in a warm humid climate.
To see if the gasket is the issue, simply put a piece of paper half inside the freezer and half out and shut the freezer. If you can pull it out easily with no resistance, there's most likely a problem with the seal.
It's also possible that the drain and/or air vents are blocked. This happens when food particles or other debris clogs up the drain hose.
