Random fan under bed with vent out of the blue 87' Rockwood

You guys nailed it! We've had the RV a year and I'm still learning about it. We only drove it once to a lot and have been here since. We have a couple cats, they've stepped on the paw-sized courtesy light switch numerous times, but never this heater switch. I guess they were cold. To be fair, it's only labeled "Aux Switch" and never knew what it did. Thank you for the help!