A method and apparatus for operating a refrigeration appliance having a plurality of compartments in direct communication with a single evaporator wherein the evaporator operates at a plurality of different evaporating pressures for controlling temperature and humidity within each of the plurality of compartments. By controlling the temperature of the evaporator used for cooling a compartment, relative control of humidity within each compartment selected for operation at a temperature greater than substantially below freezing may be obtained. In this fashion, high humidity compartments operating at a freezing temperature may be provided as well as high humidity compartments operating at somewhat above freezing. Furthermore, all compartments, regardless of their selected temperature, may be operated at a relatively low humidity if desired. Additionally, subordinate compartments, not in direct communication with the evaporator, may be provided wherein the subordinate compartments are cooled indirectly by controllable communication between the subordinate compartment and an adjacent compartment. The present invention further provides for having an isolated controlled temperature compartment wherein the controlled temperature compartment is cooled by transfer of heat from the controlled temperature compartment into an adjacent flask containing a phase change material. The flask is independently in communication with the evaporator, such that the phase change material may remain at its transition temperature.