A pneumatic valve (10) for use in a pneumatic seat (12) of a vehicle is disclosed. The pneumatic valve includes an upper housing (32) and a lower housing (38). The lower housing is slidably received within the upper housing. The lower housing has an upper surface (78) and a lower surface (79). The lower surface has an inlet stem (88), a seat air inlet/outlet stem (90), and at least a first exhaust port (94). The pneumatic valve also includes an elongate poppet (108) slidably mounted within the seat air inlet/outlet port on a first spring (106) to control air flow through the seat air inlet/outlet port. The poppet has an enlarged head portion (110) located at one end and a cam projection (113) located at the other end. A slide member (34) is supported on the upper surface of the lower housing for reciprocating movement relative to the housing to selectively control air flow therethrough. The slide member has an upper surface and a lower surface. The lower surface of the slide member has a cammed portion (68) to selectively and automatically permit rapid exhaustion of air from the seat air inlet/outlet port. The cam portion includes a detent notch (70) to selectively lock the slide member into continuous fluid communication with the seat air inlet/outlet port and the exhaust port to permit air to escape therethrough.