How do you replace a heater core for a 2004 suzuki forenza?

To replace the heater core in a 2004 Suzuki Forenza, first disconnect the battery and drain the coolant. Remove the dashboard, including the center console, to access the HVAC unit. Disconnect the heater core's hoses and any attached wiring, then unbolt the heater core from the HVAC assembly and remove it. Install the new heater core by reversing the disassembly steps, reattach all components, refill the coolant, and check for leaks.