Operating Modes

Vent Mode

With the mode knob in the "VENT" position, the vent valve is open so air can flow to the instrument panel outlet ducts.

Heater Mode

When the mode knob is held in the "HTR" position, the vent valve is partially closed. The defroster valve remains closed. As a result, air from the blower fan is heated as necessary and directed to the defroster valve which sends most of the airflow to the heater duct and some to the defroster nozzle.

Blend Mode

As the mode knob is moved into the "BLEND" area, the defroster valve moves into an intermediate range to uncover more of the opening to the defroster. As a result, an increasing amount of air flows to the defroster nozzle and a decreasing amount flows to the heater duct.

As the mode knob moves into the "BLEND" area between the "HTR" and the "VENT" positions, the vent valve moves into an intermediate range to uncover more of the opening to the instrument panel vents. As a result, an increasing amount of air flows to the vent nozzles and a decreasing amount flows to the heater duct.

Defrost Mode

When the mode knob is in the "DEFROST" position, the defroster valve moves to fully uncover the opening to the defroster nozzle and restrict the opening to the heater duct. This delivers the maximum airflow to the defroster nozzle, with only a little amount of airflow coming out of the heater duct.