102 Climate ControlPollen filterThe pollen filter cleans the air entering fromoutside and filters dust, soot, pollen andspores from the interior air if the airrecirculation sy stem 3 is activ e. The activecarbon la yer 3 eliminates most odours andharmful ambient gases from the a ir.Hav e the pollen filter replaced at theintervals spec ified in the S ervice Booklet.NoteIf the windscreen becomes fogged in dampweather, set the sy stem tem porarily asdescribed under "Defrosting and d emistingthe windows" – see p ages 98, 101.The cooling 3 operates most effectivelywith the windows closed. If the interior hasbecome extremely hot after long periods inthe sun, open windows for a short tim e sothat the heated air c an dissipate quickly.When cooling 3 (air conditioningcompressor) is switched on condensationforms, which is expelled from the undersideof the vehic le.Cooling switches off automatically at lowoutside temperatures.At least one air vent must be open w hilecooling 3 (air conditioning com pressor) ison in order to prev ent the ev aporator fromicing up due to lack of air m ov ement.MaintenanceIn order to ensure consistently goodoperation of the AC comp ressor 3 , it mustbe opera ted sev eral m inutes once permonth irrespec tiv e of the wea ther orseason. It is not possible to operate the ACcompressor 3 when outside tem peraturesare low.C ontact a workshop for a ssistance ifproblems are encountered.