Abstract: This invention provides a refrigeration system which includes in a closed loop connection a compressor for compressing a refrigerant into a condenser for condensing the compressed refrigerant into a liquid refrigerant, a control valve to controlling the discharge of the liquid refrigerant from the condenser into a reservoir, a sensor for measuring the temperature of the liquid refrigerant near the control valve, a fan for circulating air thorough the condenser, a sensor for measuring the ambient temperature of the air flow through the condenser, and an electronic control system to control various functions of the refrigeration system, including the flow of the liquid refrigerant through the condenser as function of the temperature difference between the ambient temperature and the temperature of the liquid refrigerant. During operation, a minimal flooding of the condenser is always maintained; i.e.

Abstract: A method and apparatus for controlling the capacity of a multi-stage cooling system is disclosed. The system of the invention utilizes a plurality of commonly piped compressors having common suction load wherein at least one compressor being a variable speed compressor, means for establishing a single predetermined cooling stage "cut-in" pressure and a single predetermined cooling stage "cut-out" pressure, a plurality of condenser fans and a microprocessor based control means for controlling the operation of the system.