There was a theory that pollen was interacting with the evaporator coils, resulting in corrosion and leaky evaps. Don't know if that's true or not, but I retrofitted the filter to my '94 when I had it. I think the newer part numbers may have changed, but when I did it a few years ago you needed the retainer and the filter- two parts. The retainer is simply a bracket that holds the filter and slides into the fresh air opening. You may want to check to see if you already have the retainer. If yes, you may want to remove it and get the part number so that the filter you order will fit it. Installation is not difficult.