Cooling system and refrigerant control method for cooling system

A refrigerant control method for a cooling system comprising:

• a refrigerant,
• a vaporizer which is configured to absorb heat due to a refrigerant in a liquid phase being vaporized,
• a condenser which is configured to discharge heat due to the refrigerant in a gaseous phase state being liquefied, and
• a cooling target positioned in a vicinity of the vaporizer, the cooling target being cooled by circulating the refrigerant between the vaporizer and the condenser,
• the refrigerant control method comprising:
• applying a resistance to the refrigerant flowing inside a pipe passage ranging from the vaporizer to the condenser,
• measuring a difference between a temperature of the refrigerant inside the pipe passage on an upstream side thereof before the resistance is applied to the refrigerant and a temperature of the refrigerant inside the pipe passage on a downstream side thereof after the resistance is applied to the refrigerant, and
• reducing a flow rate of the refrigerant in the liquid phase to be supplied to the condenser in a case where a temperature difference is equal to or greater than a threshold value.