Is there a storage cabinet above it that you can get into and trace where it goes?
You might blow some air up through it and see what happens, but be careful, you could blow it off of whatever it's attached to.
Might also be for the A/C if you have it.
1988 Coleman Sequoia - popup (1987-2007)
2012 Roo19 - hybid (2012-2015)
2016 Mini Lite 2503S - tt (2015 - ???)
2011 Traverse LT, 3.6L, FWD
2009 Silverado Ext Cab, 5.3L, 4x4, 3.73
2016 Silverado 2500HD Dbl Cab, 6.0L 4x4, 4.10