For 1990-2009 cars

The rear air adjustable struts are constructed with a rubber-like air sleeve attached to the dust tube and reservoir. This sleeve forms a flexible chamber which extends the strut when pressure in the chamber is increased. When air pressure is reduced, the weight of the vehicle collapses the strut. In order to maintain proper operation and reliability of the air adjustable struts, a minimum system pressure of 48 kPa (7 psi) must be maintained at all times.