Dual pump down cycle for protecting a compressor in a refrigeration system

A control system for operating a refrigeration system including a compressor for compressing gaseous refrigerant supplied to the compressor from an evaporator which receives refrigerant from a condenser, comprising:

• an expansion valve for controlling refrigerant flow from the condenser to the evaporator, said expansion valve having a fully closed position which substantially prevents refrigerant flow from the condenser to the evaporator;
• and
• a control means for turning the refrigeration system off and on, for moving the expansion valve to its fully closed position whenever the refrigeration system is turned off, for generating and supplying a first control signal to the refrigeration system compressor to run the compressor for a first preselected time period sufficient to reduce refrigerant pressure in the evaporator to a first desired level whenever the refrigeration system is turned off and the expansion valve is moved to its fully closed position by said control means, and for generating and supplying a second control signal to the refrigeration system compressor to run the compressor, while maintaining the expansion valve in its fully closed position, for a second preselected time period sufficient to reduce the refrigerant pressure in the evaporator to a second desired level prior to said control means turning on the refrigeration system.