We don't have a Furrion but most TVs have a setting that will change screen dimensions. The old setting, before flat screens was 4:3.
This is copied from Samsung:
- 16:9: Display the picture in widescreen aspect ratio.
- Custom: Customize the aspect ratio manually.
- 4:3: Display the picture in Standard (low-def) aspect ratio. Suitable for VHS and standard-def broadcasts.
- Fit to Screen: The full image will be displayed. No part of the image will be cut off.
Note:The availability of this function depends on the Picture Size Settings.
- Zoom and Position: Adjust the picture size and/or position.
If it's set on 4:3 and sometimes 16:9, you will see side black bars.
Some remotes have a button to change that screen size, others have you go into the "SETTINGS" menu.
Hope this fixes yours - we love the OE midline VIZIO in our HC