Universal refrigerant controller

Generally the present invention relates to a refrigeration system. More specifically, but not exclusively, the present invention is directed to systems and methods for controlling coolant flow in refrigeration systems and associated components. In general the present invention provides a refrigeration system and a method of controlling the refrigeration system. The system includes a coolant circuit having in series a compressor, a metering device, an evaporator coil, and sensors for determining the coolant temperature and pressure within the circuit. The system also includes a defrost system that includes a fan and/or a resistive heating element. The present invention also provides a method of operating the refrigeration system to protect the individual components such as the compressor from damage from flooding with liquid coolant. Additionally, the operating method provides a more efficient operation by using a self-adaptive defrost sequence and rapid startup sequences after the defrost periods.