I'm thinking about changing the desiccant cartridge in the Haldex AT-87192 air dryer.
The last coach we had I was able to replace the cartridge without draining any of the air lines or tanks.
In reviewing the Haldex maintenance information that came with the bus I noticed that it states "Drain all reservoirs and air lines to 0 psi." prior to servicing.
Anyone have experience with the AT-87192? Is it necessary to drain all air to 0?