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When installing a new cabin air filter - - in which direction should the airflow direction arrow on the new filter point: up (towards the roof of the car) or down (towards the floor)?

My factory-installed one did not have an arrow, the new one (MicronAir brand, made in Germany) does.

I installed it with the arrow pointing "UP".

I'm just looking for a definitive answer to the Up or Down question. Can anyone help?


BTW... it's a 2008 JustaCooper...
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I've never noticed an arrow but I wouldn't sweat it ... on a home AC the flow arrow applies to the side where the flow re-enforcement is. So the filter won't collapse.

In this situation .. not an issue

GEN1 OEM filters would only go in one way . . .

 

up is correct

 

The filter doesn't have a direction. Oh BTW watch out for that box I popped the lid of my breaking the tab and slicing the **** out of my finger. Its dangerous.

 

Well, I think "UP" is the correct answer.

As far as I can tell, the activated-carbon filter does have a specific orientation - they put the "air flow" arrow on there for a reason, right? There seem to be a couple of layers of filter medium above the carbon layer, so that dust and other crap will get caught in the filter medium before the (clean) air flows through the carbon layer. If the filter is installed the wrong way 'round, the carbon layer will catch all the dust and get clogged up first.

The plain particulate filter (no carbon) has only the layers of filter medium, so the air can flow through it in either direction and it will still do its job just the same.

So - - I'm calling "airflow arrow UP" as the correct answer for the activated-carbon filter (and not just because that's the way I put mine in!), and "either way, it doesn't matter" for the plain filter. If anyone has any better info - please share.

Thanks to those who replied.

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I just installed the a Mini branded cabin air filter in a 04 MCS (w/o auto climate control) and it fit properly with the airflow arrow on the side of the filter pointing DOWN (towards the cover/floorboard). I really don't think it would fit the other way as the bending of the filter would cause it to tear. I also note that the filter I removed was dirty on the upward side of the filter which implies to me that the airflow is going down, not up. This disagrees with one of the video tutorials on the net also.

- Mark

 

i think down is the proper way. the air comes from the top through the cowing at the bottome of the windshield and then passes through the filter and into the vent system. so since the air is coming from the top the air flow is down the arrow shoud face down. i just replaced my filter today and i had the arrow facing down.

 

I've heard that the filter is actually for re-circulating air FROM the cabin. So it basically takes air from the cabin, sucks it in, and pushes it back out from the air vents. To me, that makes sense...though I would also think there should be a filter for the air coming in from the outside in the first place (if it really does).

The filter I got didn't even have air flow directions printed. It did have a lighter and darker side, and I put the darker side (charcoal) toward the ground. Hopefully that was correct. I should have looked at the previous one Mini had installed. Or just call to double-check.

 

wasn't nice that the early filters only fit one way . . . they had a plastic frame which fit into slots.



or

what the heck difference does it really make . . .

on my home a/c it reflects which side has reinforcement against flow pressure ....

but in this case; borders on silly.

filter material is the same either way.

 

I confused myself with this to; just pay attention to your old filter when you are removing it. The dirty (dirtier) side is the side air flows in on.