Is there an inyan to place a Mezuza on the door of a walk-in fridge or freezer? If the Mezuza is placed inside (the above), can it not become posul to the cold temperature?
A walk in fridge is similar to any room used for storage which is obligated in a mezuza. A freezer however is a place completely unfit for any time of living quarters is exempt according to most authorities. In either case the mezuza should be put on the outside if possible, otherwise it should be wrapped very well and sealed to keep out any moisture from the mezuza.