Inflatable seat cushion assembly

An inflatable seat cushion assembly includes a seat cushion having a plurality of inflatable compartments and a manifold block having integrally formed therewith a pressure manifold with a common inlet for connecting to a source of pressurized fluid and a plurality of lateral outlets, each for establishing fluid communication between the fluid source and one of the compartments through one of the inlets. An exhaust manifold is also integrally formed with the manifold block. The exhaust manifold has a common outlet for exhaust of spent fluid from the compartment and a plurality of lateral inlets, each for establishing fluid communication between the compartments and the common outlet. The exhaust manifold is separate from the pressure manifold. Control valves are positioned between each lateral inlet and a corresponding lateral outlet. Each control valve is selectively adjustable among positions where its associated compartment communicates with the lateral inlet for inflating the compartment; where the associated compartment communicates with the corresponding lateral outlet for deflating the associated compartment through the exhaust manifold; and where the associated compartment communicates with neither the pressure source nor the exhaust for maintaining the associated compartment at the desired pressure.