Why does ice sometimes form inside the refrigerated display window?
Because a refrigerated display window is designed for a limited use over time; it must be used to keep the ingredients it contains only during the hours of service.
At the end of the "shift" the ingredients must be placed inside a chilled cabinet or counter.
If the refrigerated display window is used on a continuous basis, since it has no automatic defrost system, you may find ice forms inside; if this happens switch the cabinet off and wait for the ice to melt.
Is it normal for the fan to work all the time?
The refrigerated display window is designed to work in extremely hot environments, usually close to ovens,
which is why the fan works all the time, maintaining an optimum performance even close to high temperature sources.