Left rear never sits level, its always an inch or more lower then the right. on 2006 Hummer H2

Left side ride height sensor has been replaced, left rear airbag been replaced twice. Within a few minutes left side is completly empty, dealer cant find any leaks, computer doesnt flash any codes, computer says truck is level.

Asked by for the 2006 Hummer H2
you have a bad air vale in compreser or bad seal
or one of the lines is leaking. it has to be really bad leak to loose airthat fast should be easy to diag