Air ride is actually a very simple system not much to go wrong. The ride height control valve is connected to the frame on one end and to the axle housing on the other end. The RHCV is going to be the most common item to mess up in the system. It's the one piece that moves with every little bump. So from either wear or internal debris they fail, I would always suspect it first. If something is not so obvious spray soapy water on the air bags, rhcv and coupling's/connection's etc until you see bubbles.
As far as adjusting the Ride Height Control Valve, I would be very careful you have to consider the drive line angles, they are set at the factory. If you feel the need to adjust I would take measurements between the axle and frame before you do. If they are out of whack you will have very bad drive line vibration.
There are several ways they are setup but they are all basically the same.