If you suspect that your Fantastic Fan is not operating because of the dome interlock switch being loose and not providing a good ground, you may be able to tighten the switch nut from inside the van.
I removed the screen; mine is clipped in. I opened the dome to provide access to the switch. The fan was turned off.
I used a Craftsman 44539 10 mm / 11 mm 12 point combination wrench. It is 3 7/8 inches long with a 10 mm open-end and 11 mm box-end bent at an angle.
The 11 mm box-end went over the switch and down around the nut with the natural wrench bend putting the 10 mm end of the wrench lower into the van.
Using the fingers of one hand to turn the wrench and the fingers of the other to push the box-end down around the nut, it took about one inch travel of the wrench open-end moving counter-clockwise if looking up to tighten the nut and restore a good connection. Fingers work between the fan blades.
I found the following, interesting to me, Q&A words on the Fan-Tastic Vent web site:
Q CAN I DRIVE WITH MY VENT OPEN?
A YES! It is best to have the dome completely open. There is a lifetime warranty on the dome.
Chuck Sorensen
Buellton, California
2012 Excel TS