Believe it or not, there is a filter in the HVAC system of many vehicles, that filters the cabin air when your heat or air is on. When you have your HVAC set to outside air, it also filters the dust and stuff from the outside air before putting it inside your vehicle. That sounds important, doesn't it? The fact is that they never check these filters when you take your car in for routine service (even at dealers), even though it is recommended that this filter be replaced annually,
We have two GMC Acadias, a 2010 and a 2012. It turns out that, though the vehicles are almost identical, our 2010 does NOT have a replaceable filter, but the 2012 does. It fits the 2012 exactly as the original, with the improvement of the activated charoal, Happy that our 2012 filter finally has a new filter (first time replacing it since new). High quality and at a very good price. Will be ordering another.