Raising the height control valve lever in an air suspension system signals the air bags to further inflate, increasing their volume and pressure to adjust the vehicle's height
When the height control valve lever of an air suspension system is raised upward from the horizontal position, it typically signals the system to further inflate the air bags. This action does not reduce chassis system pressure or dump the suspension air circuit. Instead, it increases the volume and pressure within the air bags to adjust the height of the vehicle accordingly.
The principle behind this is similar to inflating a tire: as air is added, the volume increases until the tire walls resist further expansion, at which point additional air leads to an increase in pressure. However, in the fully inflated state, any increase in temperature can further increase the pressure inside the air bags or tires.