No re the fan, it adds complexity re powering it & should it ever seize...
o Most DC fans are designed for 72-200hrs locked rotor
---- eg, current limiting by power-cutout, timer, restart, repeat
o However AC fans use thermal cutout for 24-72hrs, and get very hot
---- AC fan when not turning do not have current limiting
---- eg, they use bimetallic or other methods to prevent overheating

They are used in such applications, inside (-40oC rated) & outside.
However for DIY use you can find a less complicated solution...

Simply use natural convection...
o Most fridges only have adjustable feet at the front
---- at the rear they sit flat on the floor obstructing airflow
---- so convection is forced to use the side gaps, scavaging
o Instead place the fridge on even slim floor spacers either side
---- so creating an air gap direct to the compressor & up over the rear

Fridges do not dissipate much heat (freezers do, particularly if they
use a hot-gas auto-defrost system which can give a big heat spike).
--
DB.