Control device for refrigerated display case

In a refrigerated display case comprising an external housing, an internal housing within the extension housing for storing merchandise, a front opening for access to the interior of said internal housing, passage means formed between said external and internal housing which includes inner and outer conduits interconnecting respective inlets and outlets extending across opposed edges of said front opening, circulating means for driving air around said passage means through said conduits in the form of inner and outer air curtains and a refrigeration unit to cool said display case, said refrigeration unit having a compressor, a condenser and first and second evaporators, the improvement comprising:

• said first evaporator being disposed in said inner conduit;
• said second evaporator being disposed in said outer conduit, the inlet side of said first evaporator being coupled to the inlet side of said second evaporator by a first passage line in which the outlet side of said first evaporator being coupled to the discharge side of said second evaporator by a second passage line in which third and fourth check valves are disposed in series, said first and second passage lines being connected to each other by a third passage line;
• said condenser being coupled to the inlet side of said first and second evaporators and said first and third passage lines by a plurality of valve devices;
• said compressor having its discharge side coupled to the inlet side of said condenser and its suction side connected to the outlet sides of said first and second evaporators through a plurality of valve devices;
• and
• control means for controlling the operation of said refrigeration unit by operating said first and second evaporators in series and in parallel in accordance with a predetermined program.