Does my 04 WRX have a cabin air filter to filter the interior air?
If so where is it located and how do you install a new cabin
air filter? Thanks.

 

I belive it does, it should be right behind the glove box. You will need to take it off to get to it. I have an 04 as well and I am going to change mine out soon. I will let you know what happens.

 

If my car does have one I haven't changed it since I got my car.
If I can change the cabin air filter myself I will.

 

When my friend bought his '04, it was listed as a factory option, so I don't think that you're WRX is going to have one. I've read that people just buy an A/C unit filter from a hardware store and cut it to fit.

 

The filter is in fact an option and your car may or may not have it. If the dealer installed it there should be a sticker on the doorpost to indicate its presence, but the only way to know for sure is to remove the glovebox and check.
Regardless of whether it's there or not, you don't have to buy the filters from the dealer at $40 or so a pop, make your own. More info here-
http://forums.nasioc.com/forums/showthread.php?t=476514

 

how the hell can you make a car without a cabin filter?

 

Not sure if this helps but they are for the forester...

Procedure for extracting/replacing in-cabin filter:
LINKY

Procedure for making a rewashable in-cabin filter:
LINKY

 

The Forester filter is different from the Impreza filter. The NASIOC link I posted is for the Impreza.
Jakes, a lot of cars do not have cabin filters. While these are becoming a more common item on lower and mid-range cars they are not yet universal.

 

Yes, I am aware of that...just wanted to add a link that maybe someone could get a better pic or some information to help w/ making a reusable filter.