As Stripit said--not sure what you mean by an 'attic' fan. There are only vent fans IN the ceiling vents, or a regular house fan in the living area.
RVs don't have 'attics' such as a stick house does...
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired