What is the best way to change a heater core on a 92 Cadillac Eldorado?

To change the heater core on a 1992 Cadillac Eldorado, start by disconnecting the battery and draining the coolant from the cooling system. Remove the dashboard and center console to access the heater core, which is located behind the firewall. Detach the heater core hoses from the engine compartment, then unbolt and carefully remove the old heater core. Install the new heater core by reversing the steps, ensuring all connections are secure and refill the coolant before reconnecting the battery.