A cooler apparatus includes: a coolant passageway; a water pump that circulates coolant in the coolant passageway; a thermostat that includes a heater that heats a temperature sensitive portion; and a controller. The controller is configured to drive the water pump and cause electric current to flow through the heater at a first energization amount when an operation in which the coolant is injected into the coolant passageway is started. The controller is also configured to stop electric current to flow through the heater if the water pump races when the electric current flows through the heater at the first energization amount.