According to the parts catalog, it's located behind a panel to the right of the bottom of the refrigerator. It's #87 in the parts catalog. Click on the down arrow next to "Ceiling and Roof" and then click on interior. Then click on #87 and you should see the location highlighted.
Cortona3D Solo Universal Viewer
The parts catalog is a great reference for stuff like this.
Winnebago also provides online access to wiring and plumbing diagrams, etc: