I couldn't get over how hot the air is coming out of the top side vent in normal temperatures (75 degrees). There should be a fan on every fridge--no matter whether there' s chimney or a top side vent (like on a slide.)
When installing my new Dometic fridge, I installed a plywood piece across the width of my refrigerator cavity--going up at a 45 degree angle from the top of the fridge to the top of the side vent. I also put in weatherstripping. My RV manufacturer had a small piece of plywood pointing up toward the top of the side vent, but it was really a half hearted attempt to eject hot air. I no longer have hot air circulating around the fridge cavity in the cabinetry and the fridge is cooling fine in all weather.