I don't have a diagram, but there is a switch on the hinge side of the vent to turn off the fan when the vent closes. It can get sticky. I had to clean and lube mine yesterday. Fan wouldn't turn on.
That would be the first thing I would check.
It can be accessed by removing the cover from the bottom of the vent. It looks like a pin sticking upward on the hinge side.
This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.