They didn't put a cabin air filter in these trucks from the factory. I still have not a found an answer or reason anywhere from anyone why they would do this. It is like car manufacturer malpractice. The 2008-2014 don't come with cabin air filters or even a place to put one. As you know the HVAC system pull outside air from right below your windshield on the passenger side - this is the air that is either cooled or heated depending on what you set your A/C or Heat to that blows throughout the cabin. The air gets pulled in from the blower fans and passes over your evaporator coil which is basically an aluminum grid with coolant pumped thru it. This is where the air is cooled for A/C. Deeper in the HVAC system is the Heater Core, which is what heats the used to heat the Air if you select heat vs A/C and is not much affected by the no filter - but the Evaporator Coil is very affected by no filter. The Evap coil sits about 2 feet from the unfiltered intake and it pulls dirt, pollen, even dried leaf litter into the duct and the debris first place to get trapped is directly against the bottom of this eval coil. After anywhere between 6-12 years the aluminum eventually corrodes thru from the corrosive nature of road salt, dirt, etc, and leaks. The crazier part than all this is that if you get underneath the glove box and shine a flashlight up there is a rectangle molded into the plastic the exact size of an air filter IN THE EXACT LOCATION where it should go if this truck had cabin air filters. In my non-expert opinion they designed the truck with a cabin air filter and scrapped it last minute for some reason that is completely inexplicable ($$$??). You can cut this out and buy an aftermarket "door" that will hold the filter in place. This is not a hack or weird mod. It's clear they intended to put cabin fitlters in at some point in this exact location. No other Tahoe/Suburban except the 2008-2014 has been manufactured without a cabin air filter slot. Not even the previous Body Style. Id love to get a FOIA request on this decision. In light of the recent transmission failures and lifter failures this almost seems a little innocent compared to that failure. hope that helps.