I just did mine. I live in a colder climate and noticed that the windows were not clearing as fast, the cabin wouldn't warm up very fast and the windows would fog really easily if you tried to breathe. It wasn't like this when I first got the car. After reading the forums, it dawned on me that there is a cabin filter.
I have prepaid maintenance so I assumed the dealer had been changing it. I seem to forget the dealer I used to go to is pretty sketchy. Thankfully I don't go to them anymore. So rather than wait for my next maintenance cycle, I decided to replace the filter right away. We will have more cold weather, winter is far from over in Canada, so more airflow and faster cabin heating times are important. I have just shy of 60,000 km and the filter was filthy. Shoehorned the new one in there. T15 bit fit perfectly.
Immediately I could feel more air coming out of the vents. I'm amazed at how much that dirty filter was restricting airflow. I think I'll make this a yearly routine right before the cold temps hit. And I hope that the 2nd time around I won't have any bruised knuckles.
Anyone know the best place to pick up an air filter? In Canada, it's $40 for a Motorcraft filter from the dealer, $48 for a Napa gold filter from Napa and $33 for a Fram filter from Canadian Tire. The Fram filter doesn't fit very well and I won't purchase it next time.