I changed the cabin air filter today. I'm guessing the previous owner never did. The old filter was caked with 47k miles worth of dirt.
After I put the new filter in, I thought, gee the K&N filter for the engine probably doesn't stop half as much dirt, so i went to Walmart and bought a Fram Tough Guard preoiled paper filter and took out the K&N.
A friend of mine has a 2004 Park Avenue and today I was telling him he should change his filter. I went over to show him where on the cowl it is based on my 2000 and lo and behold, it was actually underneath the dash above the accelerator pedal.