Patent-family-91564704

A method (300) of determining a charge status of refrigerant in a refrigeration system (100) is provided, the refrigeration system (100) having a compressor (120), an expansion valve (140), a condenser side (101) for transferring refrigerant from the compressor (120) to the expansion valve (140), and an evaporator side (102) for transferring refrigerant from the expansion valve (140) to the compressor (120). The method (300) includes determining at least one performance characteristic of the refrigeration system (100) when refrigerant is prevented from flowing from the condenser side (101) into the evaporator side (102), and determining a charge condition in the refrigeration system (100) when one or more predetermined criteria are met in accordance with the performance characteristic.