Automatic Temperature Control (ATC) System

INTRODUCTION
The Automatic Temperature Control (ATC) system provides automatic regulation of the vehicle interior temperature. The operator selects "set temperature", on which the regulation is based, regardless of the outside temperature changes. This is done by utilizing a microcomputer, also referred to as the automatic amplifier, which receives input signals from several sensors. The automatic amplifier uses these input signals (including the set temperature) to automatically control the ATC system's outlet air volume, air temperature and air distribution.

FEATURES
Air mix door control
The air mix door is automatically controlled so that in-vehicle temperature will reach, and be maintained at the operator selected "set temperature". For a given set temperature, the air mix door position will depend on: Ambient temperature, in-vehicle temperature and amount of Sunload, and intake air temperature.

Fan speed control
Blower speed is automatically controlled based on temperature setting, ambient temperature, in-vehicle temperature, amount of sun load and air mix door position.
With FAN switch set to "AUTO", the blower motor starts to gradually increase air flow volume.
When engine coolant temperature is low, the blower motor operation is delayed to prevent cool air from flowing.

Intake door control
The intake door position will be determined by: Ambient temperature, in-vehicle temperature, and whether the compressor is ON or OFF.

Outlet door control
The outlet door position will be determined by: Ambient temperature, in-vehicle temperature, and amount of Sunload.

Compressor clutch control
The compressor operation (ON-OFF) will be determined by the ambient temperature and intake air temperature.

Recirculation switch
When recirculation switch is pressed, intake door is fixed at recirculation position.

Self-diagnostic system
The self-diagnostic system consists of five steps. Each step can be accessed by pushing the switches on the automatic amplifier.
STEP 1: Checks LEDs and segments of the display.
STEP 2: Checks each sensor circuit for open or short circuit.
STEP 3: Checks mode door position and intake door position.
STEP 4: Checks operation of each actuator.
STEP 5: Checks temperature detected by each sensor.
AUXILIARY TRIMMER MECHANISM: Set temperature trimmer.

CONSULT operation
In addition to AUXILIARY TRIMMER MECHANISM in Self-diagnostic system, recent changes have made it possible to use CONSULT This enables the following functions to be controlled by AUTOMATIC MODE.
STEP 1: Adjustment of highest blower fan speed
(the adjustment of blower motor voltage)
STEP 2: Adjustment of highest blower fan speed changing point
(the adjustment of the time required for cool-down)
STEP 3: Adjustment of outlet door changing point
(the adjustment of the time required to change B/L to F/D)

Memory function
With ignition switch turned OFF, the auto amplifier stores in memory the set temperature and inputs of various switches. When the ignition switch is turned ON, the system begins operation with the information stored in memory. The system, then immediately compensates for the actual operating conditions.

CONTROL OPERATION



Display screen
Displays the operational status of the system.

Auto switch
The compressor, intake doors, air mix door, outlet doors, and blower speed are automatically controlled so that the in-vehicle temperature will reach, and be maintained at the set temperature selected by the operator.

Economy (ECON) Switch
Fully automatic control with the compressor OFF. With the compressor OFF, the system will not remove heat (cool) or de-humidify. The system will maintain the in-vehicle temperature at the set temperature when the set temperature is above the ambient (outside) temperature.

Temperature Increase/Decrease And ON/OFF Switch
Increases or decreases the set temperature.
The compressor and blower are OFF, the air inlet door is set to the outside air position. Then, the air outlet doors are set to the foot (76% foot and 24% defrost) position. In the OFF position the ATC system uses the vehicle's "flow through" ventilation. It tries to maintain the interior temperature based on the last set temperature of the system.

Blower SwitcH
Manual control of the blower speed. Four speeds are available for manual control (as shown on the display screen):
low, medium low, medium high, high.

Mode Switch
Manual control of the air discharge outlets. There selections are available (as shown on the display screen):
VENT, B/L, FOOT/DEF1, FOOT/DEF2.

Ambient Switch
Shows the ambient (outside) air temperature on the display screen for 5 seconds.

Recirculation (REC) Switch
Positions the air inlet door to the recirculation position.

Defroster (DEF) Switch
Positions the air discharge doors to the defrost position. Also positions the air inlet door to the outside air position. The compressor operates at ambient temperature approx. 12° C (54° F) or above.

Rear Window Defogger Switch
Activates and deactivates the rear window defogger.