Heater Core
WARNING: This page is about a different car, the 2003 Mercury Mountaineer and 2003 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
The heater core consists of fins and tubes arranged to extract heat from the engine coolant and transfer it to air passing through the heater core.
The auxiliary climate control system uses a rear heater core which operates in the same manner as the front heater core.