 A heater core is a small radiator located under the dashboard of the vehicle, and it consists of conductive aluminium or brass tubing with cooling fins to increase surface area.Hot coolant passing through the heater core gives off heat before returning to the engine cooling circuit.The squirrel cage fan of the vehicle's ventilation system forces air through the heater core to transfer heat from the coolant to the cabin air, which is directed into the vehicle through vents at various points.