A/C Compressor Controls

When the Ignition Switch is in RUN, battery voltage is applied through Fuse 20 to the Compressor Enable Switch. This Switch is located in the A/C Control Panel and is closed when either the center or lower slide levers are moved about 1/4 of the distance away from the left position. This ensures that the A/C Compressor does not run unless there is enough air flow to prevent freezing of the evaporator.

When the A/C Select Switch on the A/C Control Panel is pressed and the Compressor Enable Switch is closed. Voltage is applied to the Compressor Clutch through the normally closed Evaporator Temperature Switch, the Low Pressure Cut-Out Switch and the High Pressure Cut-Out Switch.

The Evaporator Temperature Switch opens if the evaporator temperature drops low enough for freezing to begin. The Low Pressure Cut-Out Switch opens if the refrigerant pressure drops low enough that operation of the A/C System would be likely to damage the Compressor. The High Pressure Cut-Out Switch opens if refrigerant pressure rises to a point that is too high for normal operation.

Clutch Diode
Whenever the Compressor Clutch is de-energized, the collapsing magnetic field induces a voltage in the winding. The Clutch Diode provides a path for the resulting current.