Electronic Climate Control

The Automatic Temperature Control (ATC) System provides electronic control over all of the A/C system functions. It maintains a selected temperature fro individual driving comfort by regulating the temperature of the discharge air (floor, defrost, mix, panel). The system also allows the driver to manually set location of the discharge air and fan speed for desired comfort or specific operating requirements.

Actuator Motors

The various doors used to control air distribution are controlled by three actuator motors. The Function Control Actuator is controlled through the air flow control buttons. The motor controls the flow of the Instrument Panel, floor and defrost outlets. The REC/FRESH Actuator Motor controls the position of the REC/FRESH door and is used to select either fresh outside air or recirculated air. The Temperature Blend Actuator Motor is operated through the Temperature Control Lever. This motor controls the position of the Temperature Blend door and determines the amount of outside air that circulates through and around the heater core.

Voltage

With the A/C Switch in the ON position, a ground is supplied to the coil of the Condenser Fan Relay allowing curent to flow from the 20A AIR COND fuse to the Condenser Fan Motor and the Compressor Clutch. With voltage applied to the Compressor Clutch coil, the Clutch and Hub assembly is drawn toward a free-wheeling pulley. since the Clutch and Hub assembly is mechanically coupled to the compressor, the pulley and compressor spin as one unit.

Blower Motor

The Blower Motor circulates the cooled air from the condenser to the inside of the vehicle. With the A/C Switch in the ON position, the ATC Module supplies a ground signal to the LO-Speed [1][2]Blower Motor Relay. Current flows from the 15A COOLING Fan fuse through the Blower Motor Relay and LO-Speed Blower Motor Relay to the collector of a power transistor. Blower Motor speed is controlled by the power transistor which provides a wide range of Blower Motor speeds. Whenever the Blower Fan Speed Control is in the MAX position, the HI-Speed blower Motor Relay energizes and bypasses the power transistor. With the HI-Speed Blower Motor Relay energized, full battery voltage is applied to the Blower Motor.

Refrigerant Pressure Switch

The Refrigerant Pressure Switch cycles the Compressor on and off in response to the refrigerant temperature. If the refrigerant temperature drops below a certain value during A/C operation, the Refrigerant Pressure Switch opens and removes the ground signal to the Electronic Control Assembly (ECA) causing the compressor to stop spinning. The switch will close once the refrigerant temperature rises above a certain value.