A: To remove the heater core, start by discharging the refrigerant if your vehicle has air conditioning. Disconnect the battery cable from the negative terminal, ensuring you have the correct activation code for the stereo if it has an anti-theft system. Drain the cooling system and then disconnect the heater hoses in the engine compartment. Remove the rubber grommets where the heater core tubes go through the firewall. Take out the A/C Switch, marking the cable clamp locations for proper adjustment later. Remove the instrument panel dash pad, lower trim panels, and glove box. Take out the heater Blower Motor and, if applicable, the cooling unit for air conditioning. Remove the center duct and instrument panel reinforcement braces. Label and detach the air ducts, wiring, ground straps, and controls still attached to the heater housing. Finally, remove the heater unit and the two screws and clamps securing the heater core to the case. For installation, reassemble the heater unit and check the operation of the control flaps, correcting any binding issues. Then, reinstall the remaining parts in reverse order, refill the cooling system, reconnect the battery, and run the engine to check for leaks and proper system operation.