The refrigerator is cooled through the freezer
The refrigerator as a whole is cooled through the freezer, which is where the gas passes under high pressure and low temperature. The bodies that are there will seek thermal equilibrium with the freezer giving it thermal energy, including the air that is inside the refrigerator.
The freezer is positioned at the top of the refrigerator in order to also cool what is at the bottom.
The freezer is responsible for cooling the entire refrigerator.
The physical principle involved in this process is the transfer of thermal energy by convection. In this process, the cold air becomes denser, as its molecules are less agitated, thus occupying a smaller volume (in the air molecules); unlike hot air, which is denser than cold air due to the greater agitation of its molecules that occupy a greater volume.