Short answer
Ice machine manufacturers commonly call for a full cleaning and sanitizing once or twice a year, and more often where water is hard, the air carries flour or yeast, or the machine runs heavily. Follow the schedule in your model's manual, and use the cleaner and sanitizer it specifies. The bin and scoop need more frequent cleaning than that.
Health units generally expect ice to be handled as food, so the inside of the machine and the bin should be kept to the same standard as other food-contact surfaces. Slime, mould and scale can build up inside even when the ice looks clear.
Scale from hard water slows production and can damage components. A water filter, with its cartridge changed as often as the filter maker specifies, reduces how often the machine needs descaling.
Keep the scoop out of the ice, in a holder, and never scoop ice with glassware. Air-cooled machines also need their condenser cleaned so they keep making ice at their rated capacity.
Updated · By Norpex