A cooling system (40; 240) comprising: a housing (40; 242a-c); an evaporator (54; 254) disposed in said housing; a condenser (46; 246) coupled in fluid communication with said evaporator; a compressor (44; 244a-d) coupled in fluid communication with said evaporator and said condenser, said compressor being a pulse-width modulated variable capacity compressor and having first and second mechanical elements (84; 90) separated by a seal and being movable relative to one another to develop fluid pressure, said compressor including a mechanism to selectively break said seal in response to said control signal to thereby alter said fluid pressure developed while allowing said mechanical elements to maintain substantially constant relative movement with one another; a temperature sensor disposed in said housing, said temperature sensor operable to read a temperature within said housing; and a pressure sensor for sensing a suction pressure, wherein said suction pressure is a compressor suction pressure; characterized by a system controller responsive to said temperature sensor and coupled to said pressure sensor, wherein said system controller determines an average suction pressure over a specified period of time within each control cycle time, wherein said system controller is coupled to said compressor for providing a variable duty cycle control signal to said compressor whereby said compressor is modulated between a first capacity state and a second capacity state while operating to thereby adjust the operating capacity of said compressor for controlling said capacity of said compressor based on said average suction pressure and based on said temperature within said housing to maintain a specified temperature in said housing. a housing (40; 242a-c); an evaporator (54; 254) disposed in said housing; a condenser (46; 246) coupled in fluid communication with said evaporator; a compressor (44; 244a-d) coupled in fluid communication with said evaporator and said condenser, said compressor being a pulse-width modulated variable capacity compressor and having first and second mechanical elements (84; 90) separated by a seal and being movable relative to one another to develop fluid pressure, said compressor including a mechanism to selectively break said seal in response to said control signal to thereby alter said fluid pressure developed while allowing said mechanical elements to maintain substantially constant relative movement with one another; a temperature sensor disposed in said housing, said temperature sensor operable to read a temperature within said housing; and a pressure sensor for sensing a suction pressure, wherein said suction pressure is a compressor suction pressure; characterized by a system controller responsive to said temperature sensor and coupled to said pressure sensor, wherein said system controller determines an average suction pressure over a specified period of time within each control cycle time, wherein said system controller is coupled to said compressor for providing a variable duty cycle control signal to said compressor whereby said compressor is modulated between a first capacity state and a second capacity state while operating to thereby adjust the operating capacity of said compressor for controlling said capacity of said compressor based on said average suction pressure and based on said temperature within said housing to maintain a specified temperature in said housing.