That's the fan. I had Sportsmobile in Austin, TX. prep my van for me. Across from the sliding door they installed a window about 20"h x 30"w. The bottom 6-7 inches opened up and out like an awning. I could open it regardless of the weather. The FF had a cowl over it so it could be open any time regardless of the weather and left open when driving if desired. At night I'd open the awning window an inch or two and have the fan blowing outside air full strength into the van. It made a huge difference in being comfortable against the heat. I had a generator and roof A/C for when it was really hot but I ran it a whole lot fewer hours with that fan setup.