When Cleaning Ventilation Ducts

WARNING: This page is about a different car, the 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Setting Controls To Ventilation

Courtesy of VOLVO CARS OF NORTH AMERICA.

Set the controls to "ventilation" and run the blower fan at its highest speed.
Open one vent at a time and vacuum outside the dashboard ventilation vents.