Audi 5000S; Volkswagen Quantum

An air control valve is located in vacuum hose between air intake and intake manifold. It is used to create a high idle for cold engine operation and maintain a constant idle speed during warm engine running with A/C on or off.

The control unit is located in the under dash relay panel. It receives signals from a throttle closed idle switch, negative side of the coil, coolant temperature switch and A/C engagement switch.