Abstract: The present invention includes various types of open-air display cases for displaying, storing, and/or vending food, beverages, or other products having a movable barrier that can be automatically positioned over an open front or side of such a unit to prevent access to the products therein when temperatures or other conditions reach unacceptable levels, and methods of using such units. Embodiments of such units may include a temperature-controlled compartment having an open front or side for displaying items, an automatic barrier system that includes a barrier for covering the open portion, a motor engaged with the barrier for closing or opening the barrier, at least one sensor for measuring at least one internal condition (e.g.