Idle Control System (A/C Only)

Fig. 20 Idle Control System Wiring And Vacuum Hose Diagram:

This system prevents the idle speed from dropping when the A/C compressor is turned on.
When the compressor is on, manifold vacuum is introduced into the diaphragm chamber of the idle boost controller through the A/C idle boost solenoid valve which is activated by the compressor switch. The idle controller's diaphragm rod is retracted to open the throttle valve a certain amount. The amount of this throttle valve opening is adjusted with the idle control screw on the idle controller to maintain the original idle speed.
When the compressor is off, the A/C idle boost solenoid valve is deactivated to close the vacuum passage and the vacuum stored in the controller is released through the filter on the solenoid valve.