This is just a quick page on how to install an air filtration kit into a 2002-2003 Impreza. It likely carries over to other years as well- if you use the G3210FE100 filter, these instructions should work for you as well. As a bonus, you can use these instructions to replace a blown out glove box light or clean leaves and other debris out of your HVAC fan. If you should have any questions or comments, feel free to email me.
The air filtration filter lives behind your glovebox. There are several fasteners you will have to remove in order to access it. These are marked with red dots in the picture- one panel fastener and several screws hold the glovebox in. The bottom two are on the very bottom edge of the glovebox panel and are removed with the glovebox door shut. The others come out with the glovebox opened.
A better view of the location of the left hand side screws.
A better view of the location of the right hand side screws.
Undo this clip (push in the tab, pull the connector apart) to free the glove box from the wiring for the glove box lamp. This is how you would also replace this bulb were it to blow out.
With the glove box out of the way, you need to unplug the wiring harness to the HVAC fan in order to clear a path to the filter's final location. There is a push in clip on the right side of the connector, then it just pulls out.
Next, undo the two clips holding on the filter door. Pull down towards the floor on the very edge of these clips, then towards you, and the whole door will come free.
The door and a few loose screws as they sit removed. Slide out the old filter (if present) with a gentle tug on it.
Here is a shot of your HVAC fan, aslo known as the "squirrel cage" because of it's shape. This is where leaves and debris may collect (or mouse nests if the car sits for a long time in storage) and cause noise or buzzing sounds. Now is a good time to clean it out if anything has gotten in this far.
Finally, just slide your new filter into place. At this point, it would be good to put the cover back on and plug the blower motor back in and test the fan at all speeds, just to make sure you don't have any odd noises. You should not, and can reverse the rest of the steps to complete the job.