Yet another 1st gen cabin filter mod

Hey, just figured I'd share my attempt at doing a custom cabin filter mod for a 1st gen ('98 in my case)...

I'm in the middle of overhauling my A/C. When I got into the evaporator, I was shocked to find that there's basically zero filtering of the outside air going into the cab. My evaporator box & blower were both full of random crap; pine needles/leaves, pebbles, dirt, dead bees/bugs, etc. Now I know the reason why all of my A/C ducts have become caked in dirt & the cab gets crazy dusty after going off-road.

Anyway, I decided to put the filter in the gap between the blower fan & the 'baffle/damper' box that switches between 'fresh air' & 'recirculate' modes. This way, I get filtration in both modes, instead of just filtering the outside air by shoving a filter higher up in the cab's 'air intake' hole. Doing it this way will make it easier to access the filter when I eventually need to pull it out for cleaning.

Basically, I designed a couple of plastic grills that snap onto the lip of the metal blower duct plate, which are meant to hold a piece of filter foam that gets sandwich'ed between them. The lower grill can be un-snapped & removed in order to allow for pulling the foam out for cleaning.

It's a tight fit, but I managed to get the clearances right so that nothing rubs; blower runs fine & the 'inside/outside air' baffle opens&closes without any issues.

For the filter, I just grabbed a random piece of foam that I had laying around (think it was some kind of packing foam) that had the right thickness & was breathable. I cut it to shape & stuffed it in. Assuming this works, I'll eventually try to get some actual filter foam that's more suitable (has better flow & filtering). In the meantime, I think this should be good enough...

Will I lose some blower 'fan power' / CFM's because of the foam? Yeah, most likely, but I'd much rather lose some flow in exchange for keeping the cab a little less dusty, and the A/C system & ducts free of dirt / random crap from the outside world.

Anyway, hope this helps in case anyone is interested in doing something similar.
Now, for some pics...

views from outside the 'recirculate' intake (baffle folded up)



views from below where the blower goes

 

Best of luck depends where the truck lives be glad if you get 30 days before changing even less if you venture off road in any sand or dust .

Points for the idea for sure .

Good luck !

 

You should look into foam used for air intakes. I assume this should last a while in-between cleaning.

https://www.pegasusautoracing.com/group.asp?GroupID=AIRFILTERFOAM

 

I was in the middle of designing one of these brackets too since ShtBoxCustoms (4Runner Show) stopped selling theirs. My concern is that its placement is so close to the blower, the filter media will likely deform. I was planning on incorporating a fine metal mesh to prevent that.

What material are you using? ABS?

 

I don't currently print ABS so it's just PLA. As far as I can tell, it doesn't get warm enough in there to melt or deform the PLA, so it's good enough for me. ABS would probably be more durable & heat-resistant, so it's def a better option if you can print it.

I'm not aware of that ShtBoxCustoms design.

So far, no problems with clearance between the blower 'squirrel cage' and the filter bracket / 'grate' piece. If something gets loose & starts rubbing, I can always just pull the blower & push it back into place (removing the blower isn't that much of a hassle).

FYI I ended up getting rid of that piece of packing foam because it was too restrictive. Instead, I doubled-up a couple of sheets of filter material that I cut from a regular 20" AC / "box fan" filter. It flows much better now.

 

Good to know.

ShtBoxCustoms recently closed down their site, but they haven't produced their filter since they the war between Russian and Ukraine. I believe they were having them made in Russia before then. Anyway, their first design was flat (like yours) and it evolved into a conical filter which would fill the gap of the 'squirrel cage.' Pretty interesting... https://youtu.be/pcX9137EQas?si=dVy584NfjYzqQiti