System Description

The electronic automatic temperature control system maintains the selected vehicle interior temperature by heating and/or cooling the air.
- During A/C operation the system also reduces the relative humidity of the air.
- The driver may override the automatic mode of operation.

The Electronic Automatic Temperature Control (EATC) module, located in the instrument panel, has the following features:
- a blower speed override control for manual input
- a vacuum fluorescent display for displaying set temperature, ambient temperature, function and Diagnostic Trouble Codes (DTCs)
- an On-Board Diagnostic (OBD) feature to supply the technician with diagnostic trouble codes. These DTCs direct the technician to the inoperative component.





1 Remote Control Buttons
2 In-Car Temperature Sensor
3 A/C Electronic Door Actuator Motor
4 A/C Sunload Sensor
5 Vacuum Control Motor-(Air Inlet Door)
6 A/C Blower Motor Speed Control
7 Vacuum Control Motor-(Windshield Defrost Door)
8 Vacuum Control Motor-(Rear Seat Duct Door)
9 Electronic Automatic Temperature Control Module
10 Vacuum Control Motor-(Heater Air Damper Door)
11 A/C Vacuum Reservoir Tank and Bracket
12 A/C Ambient Air Temperature Sensor and Bracket

With the use of a microcontroller, the Electronic Automatic Temperature Control (EATC) module analyzes input from the following major sources:
- temperature, function and blower selection (made by the vehicle occupants)
- in-vehicle temperature
- ambient temperature
- sunload
- vehicle speed
- engine coolant temperature

Using these inputs, the microcontroller determines the correct conditions for the following outputs:
- A/C clutch engagement
- blower speed
- air temperature blend door position
- heater air damper door position
- windshield defroster door position
- air inlet duct door position