A/C System - Manual

Blower Controls

With the Ignition Switch in RUN, voltage is applied to the Blower Motor. With the Blower Switch in OFF, there is no ground connection to the motor. When the Blower Switch is in LO, current flows through three resistors to ground. In MED-LO, current flows through two resistors to ground. In MED-HI, current flows through one resistor to ground. In HI, current flows directly to ground.

A/C System

The A/C System is turned on or off by depressing the Blower Switch. When the Blower Switch is depressed and latched, current flows from Fuse 7 through the A/C Switch, the Clutch Cycling Pressure Switch, and the WOT (Wide Open Throttle) Cutout Relay to the A/C Clutch Field Coil. The clutch engages and the A/C System turns on. The A/C ON Indicator light in the switch illuminates. When the switch is depressed again and disengages, current to the A/C Clutch Field Coil stops and the Indicator light turns off.

A separate micro-switch inside the A/C-Heater Control Assembly automatically engages the A/C Clutch, but not the A/C ON indicator, when the Defrost mode is selected.

The A/C System is monitored and regulated by the Electronic Engine Control(EEC) Module. The EEC Module, working through the WOT Cutout Relay, disengages the A/C Clutch under any of the follow conditions:

1) immediately after start-up;

2) during wide open throttle conditions to provide extra engine power;

3) when engine coolant temperature approaches an overheating condition;

4) when engine idle RPM approaches stall speed; and

5) at high engine speeds.