2013 Chevy Express 3500 LT No Air From Dash Panel Vents

First, I apologize for how many times I said 'um' in this video! That's me trying not to speak like an angry Marine and trying to sound unthreatening.
Also, I had already taken things apart before I figured out how to fix this, but I still hope I made it simple enough to understand where and how.
I also didn't show the end result in the video, but this definitely fixed it. It was a hose that runs in between the battery and the rear side of the engine compartment. That hose connects to a softball-shaped black ball that's located under the battery shelf.
I don't believe that you have to remove the battery or the coolant reservoir, but it made things much easier for me. Not sure of its technical workings, but the function is clear; it makes the air from the dashboard vents blow with that hose connected to it.
I head this helps!