Inside vent noise 2015 GMC 2500HD SLT Duramax

[ronnieb53]

There is a very loud intermittent air vent noise coming into the cabin while driving at speed with windows rolled up. AC can be on or off and this noise will begin and get so loud it drowns out cell phone calls and radio. Truck is brand new and started this on the first run with only 42 miles on the truck.

[Doug_Scott]

What did the dealer say when you took the new truck back for the defect causing the noise? With 42 miles on the truck, I would have taken it back at first occurrence of the sound, very likely before the truck even got home according to your timeline. Virtually all phones have the ability to record video with sound, when the sound starts, start recording it. This may require you to have a passenger that knows how to start recording since it is not safe to start this while also driving the truck, and if you stop the truck to start recording, you know the sound will not happen now.