Mercury F5TZ-18476-A Heater Core Assembly

The heater, which is the engine coolant circulation, is used to warm the passenger compartment. The air flows through an opening in the cowl and then a blower motor forces it through the heater core where heat is absorbed. This air is mixed with varying amounts of unheated air. Thus, heating air enters compartment for passengers which is also blown into them. Finally, there are some doors in the heating system that affects floor airflow and what comes out of the defroster outlets and instrument panel louvers.