Our Samsung refrigerator started making a terrible sound. I pulled the unit out and found that the air intake was clogged with dust. This created a domino effect and caused the upper ice maker to freeze up and ice to form around the fan. I vacuumed the back and sides of the refrigerator and defrosted the ice maker. The fan also defrosted and now is running smoothly and quietly. I did order a replacement fan, and I will keep it and replace it the next time it acts up. The bottom line is that if your refrigerator is in an enclosure, make sure you do your routine maintenance and clean and vacuum the dust out of the intake grill on a regular basis.