Temperature Knob

When the control assembly temperature knob is in the BLUE (cold) zone, the air delivered by the system is unheated. When the temperature knob is in the RED (hot) zone, the air passing through the heater module is heated before the air is discharged. Placing the temperature knob in the Intermediate positions results in a mixture of heated and unheated air, allowing for more moderate air temperatures.

As the temperature knob is moved away from the BLUE (cold) zone, an electronically controlled temperature valve in the heater module opens to allow an increasing amount of air to pass through the heater core. The farther the temperature knob is moved toward the RED (hot) zone, the greater the air flow through the heater core. Heating a greater portion of the total airflow in this manner results in a warmer discharge of air from the outlets.

When the temperature knob is fully in the RED (hot) zone, the temperature valve blocks off the passage that allows incoming air to bypass the heater core. All of the airflow then passes through the heater core for maximum heating. This method of temperature control provides a very rapid response to any change in temperature selection once the engine is warm.