Cooling device and control method for cooling device

A cooling device using a refrigeration cycle in which a refrigerant is circulated through a heat receiver, a compressor, a heat radiator, and an expansion valve, the cooling device comprising:

• a gas-liquid separator configured to perform gas-liquid separation on the refrigerant supplied from the expansion valve;
• a pump configured to send a liquid phase refrigerant separated by the gas-liquid separator to the heat receiver;
• and
• a control unit configured to control opening and closing of a refrigerant flow path of the refrigeration cycle, and an operation and stop of the compressor and the pump,
• wherein the control unit starts the operation of the pump on condition that a net positive suction head of the pump has reached a predetermined value or more, and
• wherein the control unit calculates the net positive suction head from detection data of a pressure sensor and a temperature sensor, the pressure sensor being configured to measure a pressure of a liquid phase portion between the pump and the gas-liquid separator and inside a bypass valve pipe configured to connect a front and a rear of the pump, the temperature sensor being configured to measure a temperature of the refrigerant.