exterior dryer vent cleaning

[Wil Pace]

Does anyone have any tips for cleaning dryer vents from the exterior of buildings?  I typically clean out the vents using a 12' brush from the inside of each unit in my small multis.  Simple job, but its a huge pain pulling the dryer out enough to get access (W/D is in the bathroom - very tight) not to mention scheduling a time to do it in occupied units.

Is there an effective way to clean out the vent from the outside?  Would love to be able to accomplish this task without disturbing the tenants.  If I used the 12' brush, I assume it would just push all the lint back up to the dryer connection.  Maybe a vacuum hose?

Thanks!