Pull the fuse at the DC Control Panel. Use a jumper to short + to - at the reefer connection point. Do a continuity check from the load side of the fuse to ground. No continuity? You have confirmed your suspicion. Now time to start wire tracing.
The part that makes no sense is that you have lights out as well. There should be no lights on the reefer circuit, but I did use the "should" word talking about an RV.
__________________
|