Operating Modes

The driver can manually select different modes of operation.

^ OFF.
^ AUTO.
^ VENT.
^ FLOOR/WINDSHIELD.
^ MID/FLOOR.
^ MID.
^ FLOOR.
^ FRONT DEFROST

When operating in AUTO mode, the heater and A/C programmer can operate in several additional modes:

^ MID/FLOOR.
^ MID.
^ FLOOR.
^ FRONT DEFROST.

The heater and A/C programmer can also access three purge modes when certain conditions exist.

Off Setting
When the climate control system is operated in the dual zone mode and the OFF button is pressed once, the dual zone function will turn off. If the OFF button is pressed twice, the whole climate control system will turn off. This means that the blower motor and A/C compressor will be turned off.

When the vehicle is moving, air flowing over the vehicle increases air pressure just ahead of the windshield so some air is forced into the outside air inlet, through the heater and A/C module assembly, and out the floor and windshield outlets.

Temperature control circuitry is still activated so that the heater and A/C programmer operates the air mix valve and attempts to match the inside and SET temperatures. Since the compressor is not running, system air can be warmed but not cooled.

Auto Setting
The blower motor is turned ON and blower speed is automatically controlled by the heater and A/C programmer. The driver can override automatic blower control by pressing the fan speed switch.

The heater and A/C programmer evaluates information supplied by the heater and A/C control and its network of sensors and determines whether MID/FLOOR, MID, or FLOOR mode is required. The programmer then energizes the mode actuator to enter this mode.

Information supplied to the programmer also determines whether outside air is drawn into the system or inside air is recirculated.

Floor/Windshield Setting
The A/C compressor is activated if outside temperature is above 6°C (43°F) and runs to keep the evaporator core at about 1°C (33°F), as long as the VENT button is not pressed.

The heater and A/C programmer opens the defroster door, positions the air inlet door to the outside air position, and positions the A/C door so air is discharged through the floor outlets.

The blower pulls outside air into the system and forces it out the floor and windshield outlets.

Mid/Floor Setting
The A/C compressor is activated if outside temperature is above 6°C (43°F) and runs to keep the evaporator core at about 1°C (33°F), as long as the VENT button is not pressed.

The heater and A/C programmer closes the defroster door, positions the air inlet door to the outside air position, and positions the A/C door so air is discharged through the A/C vents and Floor outlets.

The blower pulls outside air into the system and forces it out the floor and instrument panel outlets.

The heater and A/C programmer determines the proper air discharge temperature and positions the air mix valve accordingly.

Mid Setting
MID mode can be accessed by the heater and A/C programmer when it is operating in AUTO mode.

The A/C compressor is activated if outside temperature is above 6°C (43°F) and runs to keep the evaporator core at about 1°C (33°F), as long as the VENT button is not pressed.

The heater and A/C programmer closes the defroster door, positions the air inlet door so that outside air is pulled into the system. The A/C door is positioned so that air is discharged through the A/C vents.

The heater and A/C programmer determines the proper air discharge temperature and positions the air mix valve accordingly.

Floor Setting
The heater and A/C programmer closes the defroster door, positions the air inlet door to the outside air position, and positions the A/C door so air is discharged through the heater vents. A small amount of air will also be discharged through the windshield outlets.

The heater and A/C programmer determines the proper air discharge temperature and positions the air mix valve accordingly.

Front Defrost Setting
The blower motor is turned ON and blower speed can be manually adjusted using the fan speed switch. The A/C compressor is activated if outside temperature is above 6°C (43°F) and runs to keep the evaporator core at about 1°C (33°F).

The heater and A/C programmer opens the defroster door, positions the air inlet door so the blower pulls outside air, and positions the A/C door so some air is discharged through the floor (heater) outlets.

The heater and A/C programmer determines the proper air discharge temperature and positions the air mix valve accordingly.
The A/C compressor cannot be turned off.

Recirc Setting
When recirc mode is selected, the programmer adjusts the air inlet actuator which positions the air inlet valve to the recirculate position.

Recirc mode is available for operation in FLOOR/WINDSHIELD, MID/FLOOR MID, and FLOOR modes. Recirc is not allowed during FRONT DEFROST modes as this could cause windshield fogging.

The RECIRC function will operate for the entire ignition cycle. Pressing the RECIRC button with the system OFF, returns the system to the last setting prior to being turned OFF.

Dual Zone Setting
When dual zone mode is selected by adjusting the passenger control head. The programmer operates the driver and passenger air mix valves independently. If the passenger operates the passenger temperature control knob to request a warmer or cooler temperature on that side of the vehicle, the programmer operates the passenger air mix valve actuator to increase or decrease passenger side discharge temperature if the set temperature is not the maximum hot or maximum cold setting.