A/C System - Manual

OPERATION
Blower
With the Ignition Switch in RUN, voltage is applied to the A/C-Heater Control. With the A/C-Heater Control in any position but OFF, voltage is applied to the Blower Motor through the Blower Motor Resistor thermal limiter and the Blower Motor runs.

Blower Motor speed depends on Blower Switch position. With the Blower Switch in LO, current must pass through all three dropping resistors and the Blower Motor runs at LO speed. With the Blower Switch in MED LO, one of the dropping resistors is bypassed and the Motor runs at MED LO speed. With the Blower Switch in MED HI, two of the dropping resistors are bypassed and the Motor runs at MED HI speed. With the Blower Switch in HI, all dropping resistors are bypassed at the Motor runs at HI speed.

A/C-Heater
The A/C-Heater Control has eight push buttons that control the various A/C and Heater functions. Seven of the buttons (OFF, FLOOR, DEF/FLOOR, W. DEF, PANEL/VENTS, MAX A/C, A/C) control air flow to the floor, instrument panel, and defrost outlets. The eighth button (R. DEF) activates the rear window defrost circuit if the vehicle is equipped with this option.

The A/C-Heater Control contains the Blower Enable Switch and the A/C Switch. The Blower Enable Switch closes when the FLOOR, DEF/FLOOR, W. DEF, PANEL VENTS, MAX A/C or A/C button is depressed to power the Blower Motor. The A/C Switch closes when the A/C, MAX A/C or W. DEF button is depressed to power the A/C Clutch Field Coil and engage the A/C Compressor (when the Clutch Cycling Pressure Switch is closed).

The temperature control lever moves a control cable connected to the temperature door, mixing heated and unheated (or cooled) air.

Power to the A/C Clutch Coil is controlled by the Constant Control Relay Module (CCRM). The A/C Clutch Control, located inside the CCRM, is controlled by the Powertrain Control Module and deactivates the A/C System when one of the following conditions occur:

- High engine coolant temperature.
- Low or high engine idle speed.
- Wide open throttle.
- Engine start up.