DESCRIPTION
Electronic Automatic Temperature Control (EATC) system maintains selected in-vehicle temperature. The EATC module microcomputer analyzes input from temperature/blower motor speed selection, passenger compartment temperature sensor, ambient temperature sensor, engine temperature sensor and sunload sensor. System has a self-diagnostics feature in which Diagnostic Trouble Codes (DTCs) are stored in the microprocessor memory and displayed on EATC module.
Microcomputer determines A/C compressor clutch engagement, blower speed, temperature blend door position, floor/panel door position, panel/defrost door position and fresh/recirculated air door position. A small electric motor is used to operate temperature blend door, and vacuum actuators are used to control remaining air distribution doors. A feedback circuit is used with blend door actuator, enabling microcomputer to identify door position.