An auto thermal valve (ATV) for dual mode passive cooling flow modulation according to an embodiment includes: a gas flow inlet port; a gas flow outlet port; a temperature dependent expandable element; a rod coupled to the temperature expandable element; and a valve disc coupled to a distal end of the rod, the temperature dependent expandable element displacing the valve disc in response to a change in temperature; wherein the valve disc is displaced away from a valve seat by the temperature dependent expandable element at temperatures above and below a range of temperatures to allow a flow of cooling gas to pass from the gas flow inlet port to the gas flow outlet port.