Hot coolant comes from the engine and is directed through the heater cores (6) and returned to the cooling system when the engine is running (under normal operating conditions).

The heater vent module contains components that heat the air flowing through. The heater vent module directs air to the proper ducts and outlets such as the distributor duct (upper) (1), the instrument panel outlets (2), and the floor vents (7).

The heater system provides the following features:

Outside air is drawn from the plenum into the heater vent module by the blower motor fan (3). Additional outside air (called ram air) is forced into the heater vent module by the forward movement of the vehicle and goes to the outside air inlet (5). Within the heater vent module, the air is heated as required, then routes through ducts to the proper outlets for discharge into the passenger compartment. A control assembly in the instrument panel allows the operator to control the following conditions: