Only this morning I came to the conclusion that the very poor performance of the fridge in my late '80s pop-top is due to warm air in the cabinate space, not the fridge itself. The cabinet allows warm air around both sides and over the top, with even the deflector at the top rear trapping warm air behind it. The freezer was icing-up on 240V at half setting after only 30 minutes so there's nothing wrong with the refrigeration unit, just that the fridge walls were getting hot preventing the inside from cooling. Its time to fit something to keep the warm air away from the sides and top - perhaps just thick sponge will do the trick. An exhaust fan might also be useful.

