Idle Up Control Valve: Description and Operation

The Idle-up Diaphragm, located on the carburetor, works in conjunction with the A/C vacuum switching valve (VSV) and A/C amplifier to provide additional idle speed when the A/C compressor is energized. When the A/C system is activated, the A/C amplifier grounds the VSV and directs manifold vacuum to the idle-up diaphragm. The idle-up diaphragm is a single diaphragm pot, connected to the carburetor throttle valve by mechanical linkage. The idle-up system compensates for the "load" of the A/C compressor and blower fan, and idle is maintained in the appropriate range, without stalling.