I bought my dishwasher from Sears in November of 2017. Around June of 2018 our vent fan started going bad, and because our washer was still under warranty, Samsung sent someone out to fix it for us. The guy who did the repair knew what the problem was as soon as he heard the cycle begin. He said he'd repaired tons of Samsung dishwashers with this same problem. He blamed it on poor the poor quality of the fan -- called them "cheap."
Around November of last year, the same problem stared back up, and it seems to be getting worse. There are times when the fan sounds like it is meeting so much resistance that it only turns in spurts and I'm worried it will soon stop turning altogether.
Here is an audio clip of the sound, take a few weeks ago.
This will need to be addressed by having a service technician diagnose the noise. Since it is out of warranty, you can use the following link to find a list of authorized service centers near you that can do the repair: http://www.samsung.com/us/support/service/location.