[tentcamper]

It sounds like there is a path into the camper for the exhaust. I would open both vents and stuff fiber glass insulation around the fridge and the side wall and counter. Maybe when someone added the radio or worked on the fridge they knocked the insulation out of place or remove the board.

On my unit I have piece of thin plywood that mounts from the fridge to the bottom of the counter where there is a board on the underside of counter. My board was missing a screw and the DW felt the counter was warm. I tighten up the board and all well now.