AIR Diverter Valve
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2002 Mercury Sable, 2002 Mercury Mountaineer, 2002 Mercury Grand Marquis, 2002 Mercury Cougar, and 2002 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
The secondary air injection diverter (AIR diverter) valve is used with Electric Air Pump (EAP) to provide on/off control of air to exhaust manifold and catalytic converter. See Figure. When EAP is on and vacuum is supplied to AIR diverter valve, air passes integral check valve disk. When EAP is off, and vacuum is removed from AIR diverter valve, integral check valve disk is held on the seat and stops air from being drawn into exhaust system and prevents backflow of exhaust into secondary air injection system.