2012 Reyo 25T unknown switch

I recently bought a 2012 Reyo 25t. There is a switch on the side wall below the drawer at the foot of the bed on the driver's side. Its not labeled or mentioned in the manual. It does say Dometic on the faceplate. It glows red when switched on. I can't figure out what it does. The water heater switch is on the control panel above the refrigerator. The holding tank heater is on the wall above the mattress and labeled. Anybody have one and know what it does?