A method of operating a compression refrigeration system with - a refrigerant having a temperature glide, - an evaporator, - a compressor, - a condenser, - a throttle valve, - an internal heat exchanger, wherein the internal heat exchanger is configured for transferring thermal energy of the refrigerant in the high pressure path upstream of entry into the throttle valve to the refrigerant in the low pressure path upstream of entry into the compressor, and - a control unit, wherein the control unit is configured for a) detecting one superheating of the refrigerant after exiting the evaporator and for detecting one superheating of the refrigerant upon entry into the compressor, and b) controlling the throttle valve using a control variable based on both superheating detections, characterised in that the control unit is further configured for c) detecting a refrigerant shortage, at least in the condenser, wherein the control comprises the following steps: - calculating a temperature difference between the dewpoint temperature and the boiling point temperature, called the temperature glide, of the refrigerant at the current operating point of the compression refrigeration system on the basis of a detected low pressure of the refrigerant, - calculating a temperature difference limit value relative to the calculated temperature glide of the detected low pressure of the refrigerant at the current operating point, - assessing current evaporator discharge superheating for falling below the temperature difference limit value, - providing a set value of superheating defined as a difference between the temperature of the refrigerant and the dewpoint temperature upon entry into the compressor, called compressor intake superheating, - assessing current compressor intake superheating for exceeding the set value of compressor intake superheating, - detecting a refrigerant shortage situation when both results of the steps of assessing are continuously met for a predetermined time. - a refrigerant having a temperature glide, - an evaporator, - a compressor, - a condenser, - a throttle valve, - an internal heat exchanger, wherein the internal heat exchanger is configured for transferring thermal energy of the refrigerant in the high pressure path upstream of entry into the throttle valve to the refrigerant in the low pressure path upstream of entry into the compressor, and - a control unit, wherein the control unit is configured for a) detecting one superheating of the refrigerant after exiting the evaporator and for detecting one superheating of the refrigerant upon entry into the compressor, and b) controlling the throttle valve using a control variable based on both superheating detections, characterised in that the control unit is further configured for c) detecting a refrigerant shortage, at least in the condenser, wherein the control comprises the following steps: a) detecting one superheating of the refrigerant after exiting the evaporator and for detecting one superheating of the refrigerant upon entry into the compressor, and b) controlling the throttle valve using a control variable based on both superheating detections, characterised in that the control unit is further configured for c) detecting a refrigerant shortage, at least in the condenser, wherein the control comprises the following steps: - calculating a temperature difference between the dewpoint temperature and the boiling point temperature, called the temperature glide, of the refrigerant at the current operating point of the compression refrigeration system on the basis of a detected low pressure of the refrigerant, - calculating a temperature difference limit value relative to the calculated temperature glide of the detected low pressure of the refrigerant at the current operating point, - assessing current evaporator discharge superheating for falling below the temperature difference limit value, - providing a set value of superheating defined as a difference between the temperature of the refrigerant and the dewpoint temperature upon entry into the compressor, called compressor intake superheating, - assessing current compressor intake superheating for exceeding the set value of compressor intake superheating, - detecting a refrigerant shortage situation when both results of the steps of assessing are continuously met for a predetermined time.