Use a
blower with a
bracket and then attach
flex tube. Route flex tube into tower.
Using a one inch hole saw blade, preferably cut a hole through a wall of the box that has the least chance of interfering with the refrigeration or other factors such as a wire. After you have broken the skin of one surface, stop and inspect the wall for these factors that may result in damage if you continue. Once inspected and comfortable with no obstructions, proceed through the wall completely. As to the pigtail, assure that it is long enough and connect to the motor after routing through the keg box wall. Seal the hole with silicone or plumbers putty.