How do you change a heater core in a 2000 Ford Expedition?

To change the heater core in a 2000 Ford Expedition, first, disconnect the battery and drain the coolant from the radiator. Remove the dashboard and the center console to access the heater core housing. Disconnect the heater hoses from the core, unbolt the housing, and replace the old heater core with a new one. Reassemble by reversing the steps and refill the coolant before reconnecting the battery.