Air Suspension Exhaust Valve
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
The air suspension exhaust valve is used to exhaust air from the air springs and lower the vehicle. The air suspension exhaust valve is mounted on the head of one of the air compressors. The air suspension exhaust valve is controlled by the air suspension module.