A4 and 1998-00 Passat Models
The pollen filter is used to filter the incoming air for the climate control and ventilation system. Any time the climate control system is activated, if the recirculation button is not pressed, the fresh air entering the vehicle must pass through the pollen filter prior to entering the climate control fan and air ducts.
This filter should be replaced every 15,000 miles or once a year during periodic maintenance and possibly more frequently in areas of urban congestion or for operators who suffer from seasonal allergies.
For additional information and removal procedures, please refer to the following topic(s): Chassis Electrical, Heating and Air Conditioning, Air Intake Pollen Filter.