Some believe it's because hot air travels upwards and that is why the freezer is not at the bottom. But, it because it makes it easier to organize and find your stored frozen food.
It may be possible depending on what kind of walk-in cooler you have, but in all likelihood your refrigerator won't cut it as a freezer or it will need major upgrades. To meet the new U.S. Energy Act...
A lot of home units cool solely on the freezer side, and "vent" cooling to the Refridge box side. Either the vent is blocked, or a helper fan, that pushes/pulls the freezer air is not spinning. Is...