Abstract: A closure for a service opening in a wall separating a frozen storage area from a warm area such as a kitchen or a warehouse loading dock includes at least a pair of spaced flexible curtain members. The curtains are fastened at one end to spaced parallel spring-loaded rollers positioned below the opening and are joined at their opposite ends in an elongated nozzle and connected by cables to power operated pulleys or drums positioned above the opening. The drums are declutchable from the power train to permit the spring-loaded rollers to wind up the curtains to open position and the clutch is re-engaged and the power drive actuated to unwind the curtains from the rollers to close the opening. A plenum chamber housing the rollers is pressurized to force warm side air between the curtains and out of the nozzle to create an air curtain across the opening when the curtains are open and during opening and closing cycles.