the refrigeration system 10 is shown to further include first and second check valves 40 42 respectively the first check valve is positioned at an outlet of the pwm compressor 12 and the second check valve 42 is positioned at an outlet of the condenser 18 the refrigeration system 10 as shown in fig4 operates similarly to that described above with reference to fig1 however as the refrigeration system 10 switches from the on cycle to the off cycle significant gas leaking through the compressor outlet side could produce a vapor refrigerant migration effect similar to that described above for the evaporators 24 to minimize this effect the first check valve 40 prevents vapor refrigerant migration back through the pwm compressor 12 to the evaporators 24 and the second check valve 42 assures that the liquid refrigerant in the receiver 20 stays in the receiver 20 with particular reference to fig4 and 5 a performance comparison can be made between a traditional refrigeration system without check valves 40 42 fig4 and the present refrigeration system 10 implementing the check valves 40 42 fig5 for a fifty 50 percent pwm duty cycle with an approximately twelve 12 second cycle time in particular the refrigeration system pressure responses for the pwm compressor outlet discharge condenser outlet and the pwm compressor inlet suction are shown as can be seen the pressure at the pwm compressor discharge is significantly increased and a reduction in the pressure at the pwm compressor suction is also seen during.