Climate Control System - Vehicles With: Dual Automatic Temperature Control (DATC) - System Operation

actuator shaft. The signal to the FCIM from the contact wiper indicates the position of the actuator door. The FCIM powers the actuator motors to move the doors to the desired positions. The desired door positions are calculated by the FCIM based on the set temperature, in-vehicle temperature, ambient air temperature and sunload.

When an airflow mode, desired driver or passenger temperature, fresh air, or recirculation mode is selected, the FCIM moves the actuator motor in the desired direction.

The FCIM sends a PWM signal to the blower motor speed control to regulate the blower speed as necessary. The blower motor speed control provides variable ground feed for the blower motor based on the input from the FCIM. A delay function provides a gradual increase or decrease in blower motor speed under all conditions.

AUTO

When AUTO is selected:

the HVAC system operates in a manner to achieve and maintain the temperature set by the operator. the driver and passenger side temperature doors are automatically controlled by the FCIM based on the temperature setting. the A/C compressor is automatically controlled by the PCM from information sent by the FCIM, based on the temperature setting. The A/C compressor does not operate if the outside temperature is below approximately 32.0°F (°C). the blower motor speed is automatically controlled through the blower motor speed control that receives a PWM signal from the FCIM based on the temperature setting, but can be manually overridden. the FCIM controls the air inlet door to recirculate, partially recirculate or open to the fresh air position depending on the in-car temperature and humidity sensor inputs.

OFF

When OFF is selected:

the air inlet door closes, preventing outside air and allowing only recirculated air. the blower motor is off.

MAX A/C

When MAX A/C is selected:

the air inlet door closes, preventing outside air and allowing only recirculated air. the recirculated air indicator is illuminated (recirculated air forced on). the footwell vent doors and defrost vent/register doors operate in combination to direct airflow to the instrument panel registers. the temperature doors move to the full cool position. Air temperature can be manually overridden. the A/C button is illuminated. the A/C compressor operates if the outside temperature is above approximately 32.0°F (°C) . the blower motor is commanded to the highest speed. The blower motor speed is adjustable.

PANEL

When PANEL mode is selected:

the recirculated air request button is enabled. If the recirculated air request button is selected (indicator on), the air inlet door closes, preventing outside air from entering the passenger compartment. If the recirculated air request button is not selected (indicator off), the air inlet door opens, allowing only outside air into the passenger compartment. the footwell vent doors and defrost vent/register doors operate in combination to direct airflow to the instrument panel registers. blended air temperature is available. Only when A/C compressor operation has been selected by pressing the A/C button (indicator on) can the airflow temperature be cooled below the outside air temperature. the blower motor is on and the speed is adjustable.

PANEL/FLOOR

When PANEL/FLOOR mode is selected: