Thanks to "lx22" from Friendswood, the noise is the fan/motor. I'll have a chance to look deeper in a couple of days.
And, yes, it's a Coleman.
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks