Controller
The operation of the air conditioning (A/C) system is controlled by the switches
on the control head. This console-mounted heating and ventilation system contains
the following knobs and display:
Temperature Control Push Knobs
- Raise the temperature of the air entering the vehicle by pressing the
top switch, with the red arrow pointing upward.
- Lower the temperature by pressing the bottom switch, with the blue arrow
pointing downward.
- Actuate the air mix door by an electric motor.
- Vary the mix of the air passing through the heater core with the air bypassing
the core.
Each press of a switch changes the set temperature by increments of 0.5°C
(1°F). This is shown in the temperature window on the function display.
The Function Display
This is an LCD display indicating the status of the control settings selected.
Starting from the left end of the display, the sections are as follows:
| • | Temperature setting -- Indicates the temperature set with the temperature
control knob. |
| • | Auto status - Indicates whether the system is operating in the full
auto mode or the manual mode. |
| • | Defroster icon - Indicates manual selection of full defrost mode. |
| • | Mode -- Indicated by icon, the mode chosen by the system in auto,
or by the operator in manual, is shown by an illumination arrow indicating the air
path. |
| • | A/C -- A snowflake icon indicating whether the A/C is
ON or OFF. |
| • | Fan speed -- Indicates the fan speed by illuminating a bar based
on the segment at the front, for low speed, and adding additional segments in order
up to the fifth, for high speed. |
Eight Additional Push Knobs
| • | Full defrost -- Causes the mode motors to direct all air to the windshield
and aide window outlets for maximum defrosting. |
| • | Air intake -- Switches between fresh air intake, the default, and
recirculating air. Airflow arrows on the display indicate the mode in effect. |
| | Maintains the set temperature automatically.
In this mode, the fully automatic temperature control (FATC) system controls the following
modules: |
| - | The inlet air door motor |
| • | OFF Switch -- Turns the automatic air conditioning and fan control
off. |
| • | Mode Switch -- Allows manual selection of the airflow direction.
Selection is shown on the function display. Each time the mode switch is pressed,
the next function is displayed. |
| • | A/C Switch -- Allows manual selection and control of the air conditioning
function. |
| • | Fan Control Switch -- Allows manual selection among five fan speeds. |
| • | Defogger Switch -- Turns on the electric defogging heater in the
rear window and the outside rearview mirrors, if the vehicle is equipped with heated
mirrors. |
Pressure Transducer
Pressure transducer switching incorporates the functions of the high-pressure
and the low-pressure cutout switches along with the fan cycling switch. The pressure
transducer is located in the high-side liquid refrigerant line behind the right strut
tower, between the right strut tower and the fire wall. The output from this pressure
transducer goes to the electronic control module (ECM), which controls the compressor
function based on the pressure signal.
Wide-Open Throttle (WOT) Compressor Cutoff
During full-throttle acceleration, the throttle position sensor (TPS) sends
a signal to the ECM, which then controls the compressor clutch.
High RPM Cutoff
As engine RPM approaches the maximum limit, the ECM will disengage the compressor
clutch until the engine slows to a lower RPM.
