How can a heater core in a 1996 E-250 Ford Econoline be repaired?

To repair the heater core in a 1996 E-250 Ford Econoline, first, you need to disconnect the battery and drain the coolant from the system. Remove the dashboard panel and the necessary components to access the heater core, including the hoses connected to it. After removing the heater core, replace it with a new one, then reassemble everything in reverse order, ensuring all connections are secure and the system is properly filled with coolant before testing.