I had the RV dealer install one in our bedroom. Not sure where they picked up the 12VDC - maybe from the light circuits - it may have been wired for one. We use it allot - multi speed and it can be set for air flow in or out of the bedroom.
Hi George, I Had Crossroads install a fantastic fan in our 2012 Cruiser 305SK and they picked up the 12V where the bedroom wall met the ceiling. This must have been the line for the over dresser light. They mounted the thermostat in the ceiling at that spot. It has all worked out great.