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How to: Cabin air filter replacement

34K views 31 replies 17 participants last post by  pHp 
#1 · (Edited)
I have been meaning to do the cabin air filter in my car as it will smell funny now and then when I turn on the AC or heat, plus sometimes I end up with moisture on the inside of the windshield by the defrost vents, this can be caused by moisture buildup being held by the cabin air filter(more specifically the crap stuck in it), and then when it gets cold it condenses onto the glass.

I noticed pictures were missing from the original post in the forum sticky so I figured why not.

Here's what you do, this was on an 09 MZ3, I think there are minor differences in it and the earlier 04-06 models so I'm not sure.

Get in the passenger side floor.




***OPTIONAL STEP*** Remove the glove box if you want more room, I have a big head and found it helpful when feeling up under the dash.

First open the glove box, and push down slightly on the two "linkages" that are coming out so they disengage and allow it to drop further, here's a pic of what they look like so you know what's going on:



Then you can drop the glove box a bit further, so now you fingers can pop the glove box strut off. It's just a little snap fit, be careful not to break it, push inwards on the strut linkage, but make sure you're supporting the glove box so it's not binding on the linkage(you'll just break it if this is happening). Now you can lower the glove box completely and just pull it out of there, it just hooks over the pivot point at the bottom.



Now back to the required steps...

Remove this little fastener, using a very small screwdriver to pry the middle part out will get it out without breaking it.



Pull the panel outwards and back towards you, there is a tab to the front of it that it will slide out, will be very obvious once it's out.


Then poke your head under the dash and you'll see a large black cover:



There are two little tabs toward the front of the panel you push forwards to release it so it can tilt downwards... here is a pic of one of those tabs so you can see what you're dealing with:



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#2 · (Edited)
Here's a pic of the other tab, take note of the rear edge of the black panel, it fits into a bracket. Know this for reinstallation later on.

Also in this same pic, look at the fastener at the front edge of the fuse block... you'll be removing these next:



These:



Fuse box will swing downwards:




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#3 · (Edited)
...

And you remove the connectors.

Side note: I was originally planning on just pushing the fuse box aside, but that proved to be not worth working around. There are (6) connectors total on my car, there are 2 blank spots though which cars that are equipped with a sun roof will have 2 more(mine has no sun roof). You will want to remove the connectors from the BOTTOM of the fuse box possibly before you swing it down. I really doesn't matter one way or the other.

There are two "types" of connectors, small and large... and all of the 6-8 connectors will be different colors that correspond to what part of the car the wiring is from.

There is one small and one large connector for each of the following:

Blue connectors = cockpit
Green connectors = front
Orange connectors = floor
? connector = sun roof (I do not know the color as I don't have one)

Both orange connectors + the small green connector go to the bottom of the fuse block, and then both blue connectors and the large green connector go to the top of the fuse block. IIRC the sun roof connectors would be both on top if equipped.

To release the large connectors, you squeeze the tabs and pull the lever backwards, this moves a lever and will push the connector out.



The small connectors work the same way, but no tabs to press. It does help to wiggle the lever part of the connector left to right, there are small detents on the side to discourage it from just coming undone on it's own. (no pics of this, sorry)

Here's all the connectors hanging after removing the fuse block.



Here's a super crappy image of where it says "cockpit 1" on the fuse block. Use those markings on your fuse block to match up to the correct color if you're in doubt(frankly it's kind of hard to mess up IMO since the wires normally get a "memory" and want to naturally stay in place but hey it's there if you need it).



Now you are about to start removing the bracket in the way of getting to the cabin air filter, but first remove this christmas tree fastener, it holds the carpet to the bracket(ignore the fact that I already removed the 12mm nuts, remove the christmas tree fastener first so the bracket keeps itself in place):



THEN there are (2) 12mm nuts securing the fuse block bracket to the firewall, remove them. It helps to use a 12-18" extension so you're not trying to break them loose while laying way up under the dash.



You'll find that a wire harness is/was secured to the bracket as well, I found it easier to unhook from the bracket after the bracket was loose, here is a pic of the wire harness fastener removed for a visual, but you pull the bracket out and push the two tabs toward each other so you can disconnect it from the bracket without breaking it.



NOW you can start removing the actual cabin air filter door!! Here's a pic of what you're up against:



The first thing to do is undo the connector, be careful, it usually helps to push the connector IN, then push the tab down, then pull it OUT. Otherwise use a small screwdriver to push the tab down, this connector is kind of brittle so don't rape it with your fingers. Then you can start undoing the (4) phillips head screws. Use a #2 phillips screw driver.



I stuffed my camera up in there, here is a sideways pic of where all 4 go(you can see 1 was already removed):



.......
 
#4 · (Edited)
Pull the filter door off and lay it aside(will still have wiring attached to it so don't yank it off or anything) and you'll be staring at the lower air filter:



Pull it straight outwards, and you'll hear/see a second filter fall downwards into the same place the last one was, and you pull it out too. PULL THEM OUT AND TAKE NOTE OF THE ORIENTATION(LEFT/RIGHT/TOP/BOTTOM). Match the new filters up to them. My second pic here is how they go in the car as pulled out.

My old filters were pretty craptastic:







Clean any debris/leaves/doo doo butter out of the cabin filter housing:



Then the fun part is putting the filters back in. You install the top one inwards, then push it upwards and it will not stay on it's own. I pushed it up then attempted to somewhat rotate it(up on the driver side, down on the passenger side where you can actually manipulate it) so it would wedge into place, It took a few tries but it ended up working, then I carefully slide the second filter in under it.



Then the reinstall is just reverse of removal....

*Screw the filter housing cover back on(4 screws), and reconnect the harness that was unplugged on the cover(and reroute the wire if you undid it from the one tab it's loose held into).

*Reinstall the fuse block BRACKET first with the 12mm nuts, and reattach the one wire harness fastener to the hole it was removed from. Also put the christmas tree fastener back through the carpet and into the bracket to keep it secured.

*Slip the fuse block mostly into place, attach the connectors on the top of the fuse block, then put the fuse block itself into the "tabs" on the bracket, and then screw the 2 finger fasteners in to keep it in place, and finally reattach the connectors on the bottom of the fuse block.

*Reinstall the black trim panel that covers the fuse block. It's back corners slip into a slot on the fuse block bracket, then the front has 2 tabs that snap into place.

* Reinstall the center console right side panel. Put the back tab into the slot on the HVAC housing, then reinstall the trim fastener removed earlier.

* If you removed the glove box for easier access, put it back too.

Start the car up and enjoy air that doesn't smell like a hobo's dick cheese.
 
#31 ·
I'm used to replacing the cabin filter in the glove box of a few Toyotas, using a cut-down 1" furnace filter. It takes maybe 10 minutes and costs only a few bucks. The only hard part is fiddling with the damper on the glovebox door, and even that part isn't really hard.

With this Mazda procedure, I'm leaning toward having a mechanic take out the filters and button it back up so I don't have to think about it again. If I'm in the right mood, once the weather warms up, maybe I'll do it myself. Even if the filters look good, I'm not sure I'd put them back in. I bought a 2008 recently, so I don't know the condition of the filters, or if there are even filters in there now. I'm not getting any smell, and the air flow is fine.
 
#16 ·
I did mine last weekend, I took pics and made a similar howto Changing the cabin air filter on a Mazda 3

As gross as yours is, imagine if you're car didn't come with a filter like mine, that stuff is just permanently in the car.

As it turns out the 2010+ model makes it much easier, the fuse panel isn't in the way at all. Just remove the kick panel, disconnect a wire, and remove the filter door. Super jealous.
 
#17 · (Edited)
I took mine to be done at the dealership (bundled package of things). When I got the car back, my air blower rattles now (middle three speeds).
I went back and asked if this was a coincidence (sure), and then the service gent showed me, when asked, how to install the air filters: essentially, the demonstration included him ramming his hand beneath the panels.
No screwdrivers, no panel removing, etc.
After reading this post, now I'm a little concerned....
 
#18 ·
Just wanted to say thanks for the how to w/pics. I did this today on my 04 that had no filters in it or empty brackets like shown in some pics. I bought cheap ones off eBay for $10.94 shipped which seem to work just fine. I may actually use my AC this summer.
 
#23 ·
Did this today everything went well, took about an hour because the 2 nuts on the bracket refused to budge. Mine were pretty clogged so now we'll see if the carbon activated are worth it. Though I probably will never replace the cabin filter again after all that work.
 
#24 ·
OMG, all this for in cabin filters. I thought mine on my RAM were bad, having to cut the truck to put a filter in. This is def. worse but I have no idea what the bonehead who owned it before us did in it, so I'd better place ANOTHER order with Rock Auto lol (1/day each day we've owned it so far)
 
#25 ·
Thanks for the walkthrough!

Just did this today. The only differences I found was that the '06 (and I'm assuming '04-'07 HB) has three wire harnesses. Other than that, pretty much the same. Although I did find it easier to remove the connector that goes towards the filter housing. (Sorry no pics)

Ohter than that, can confirm. Tis a pain in the ass, specially considering my huge head.
 
#27 · (Edited)
This is a great write up. Looked through the downloadable 2010 Mazda 3/Mazdaspeed 3 Workshop Manual, and it lists that the cabin filter should be replaced every 2 years. Further searching, there is nowhere in the manual that shows how to replace mine. I searched "cabin", "cabin air filter", and "filter", and other filters came up, but nothing on the cabin air filter. I am wondering if this process is the same for mine? I bet mine hasn't been replaced either, but I don't have any smell issues.

UPDATE Found Cabin Filter replacement in the workshop manual on page 07-11-3.
 
#28 ·
just replaced mine
right hand drive car, filters came out on left side footwell
i was able to just hang fusebox (pjb) out of the way
definitely could have been designed better, took around 45 minutes
looked very dirty so probably not changed in a long time
much thanks to op for this how to
 
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