Heating Circuit, Function

Component Identification:

Function
The coolant pump (5) pumps cold coolant through the engine. Here the coolant absorbs heat from the engine and is heated up. Then the heated coolant passes through the heater core (2). The air flowing through the heater core (2) is heated and flows into the vehicle passenger compartment.
The coolant flows through the coolant return (A) propelled by the heater water circulation pump (6) back to the coolant pump (5).
The major portion of the coolant does not flow through the heater core (2), but rather from the engine to the coolant thermostat (4). The water is routed through the radiator (3) or directly to the coolant pump (5) depending on the water temperature.