After searching more, I found on the lance forum> http://lanceowners.hoop.la/topic/refrigerator-switching-from-lp-to-dc apparently the switch is installed to keep the system from running on 12 volts when not wanted. TJeeper wrote My 850 camper (2015 model) has a switch on the panel above the fridge. This switch controls the DC mode on the fridge, so it cannot accidentally or automatically go to DC mode. I can also set the mode on the fridge control panel. This is a good setup. Don't all the newer (2015 +/-) campers have this switch? At this point I am satisfied and will mark the switch refrigerator 12 master and on and off positions.
Thanks
Stan