Hi Jerry67,
Welcome to the Heartland Owners Forum and Family. We have a great bunch of people here with lots of information and all willing to share their knowledge when needed.
Where are you planning on installing the fan? If in the place where a second a/c or vent would go there may be wiring already there, both 12v and 120v. Hopefully another member will jump in that has done this.
Enjoy the forum.
Jim M