I believe that all XL2 at least around our vintage have an airlock on the door. When Kevin and I were trouble shooting ours (both had problems, different solutions), I downloaded the schematics from the Prevost website, so it was not converter specific.

The airlock on an XL2 is on the top of the door, on the rear side. It is protected from operating by three things, all of which can prevent the airlock from engaging.

1. The parking break must be OFF.
2. There is a proximity sensor, that senses that the door is closed
3. There is another sensor on the regular latch which will trip it, if the latch is pulled.

Kevin's wasn't working and it turned out to be an adjustment on switch #3 above.

Mine had actually been unplugged somewhere along the way, and once we re-plugged the switches in, the lock operated normally.

Ray