Depending on the layout of your motorhome (or caravan) the area behind the fridge is open to the outside by 2 large vents. This area should! be insulated from the rest of the van to prevent draughts and also to prevent exhaust fumes when the fridge is operating on gas getting inside the van.
On my van there was a 5 to 10mm gap around the wheel arch from the back of fridge area into the habitation area which I blocked using slices of pipe insulation.
Maybe not a problem for summer months but those draughts are very annoying during winter trips away.