The ventilation for our refrigerator was simply a round approximately 7 inch hole cut into the floor of the bay with a wire mesh on the outside and a plastic (steel wool like) mesh filling the hole with a wire cover over the top. The ventilation hole was directly at the back of the refrigerator adjacent to the compressor. The fan was a computer type electric fan that had an electric thermostat. When activated the fan blew the hot air from around the compressor outside of the bay. I assume that it pulled air from the passenger compartment into the bay when the fan was running. I did not find any addition ventilation in the bay.