Why do cabin AF's get WAY dirtier than engine AF's

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This has probably been discussed before but I'm too lazy to search currently. I just changed mine on my Civic again and the cabin versions are clogged after the 30k recommended interval. Engine: could probably double it and it would still be fine.
 
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This is my question too, all my cars' cabin filters are clogged after less than 30k miles, while the engine air filters are usable for another 20-30k miles. Is it most engine air filters have more filter surface so that it doesn't look as dirty as cabin filter with less filter area ?
 
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I have been wondering the same thing: wife's Sonata has FILTHY cabin filter after 15,000 miles, engine filter nearly clean after 20,000 miles. Driving through the same air, seems odd. John
 
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Even though you may think an engine air filter is clean after 20-30K, a very wise man who knows about such things recommends that you change it every 10k.
 
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I think a lot less air flows through the average automotive air cleaner than does through the evaporator side of the AC system. If you figure an average horsepower output of a car engine at 40 hp for the life of an air cleaner (that's probably higher then average), that's an average of about 60 cfm airflow. I think the passenger compartment blower moves a lot more air than that.
 
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My cabin filter is a thick hepa filter. Its a lot thicker than a engine filter. There is a lot more element packed into it so I would think it gets dirty because it filters a lot more out of the air.
 
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 Originally Posted By: aaxb970
My cabin filter is a thick hepa filter. Its a lot thicker than a engine filter. There is a lot more element packed into it so I would think it gets dirty because it filters a lot more out of the air.
 
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 Originally Posted By: aaxb970
My cabin filter is a thick hepa filter. Its a lot thicker than a engine filter. There is a lot more element packed into it so I would think it gets dirty because it filters a lot more out of the air.
It can't filter a lot more because a good paper engine air cleaner element catches over 99% of the crud in the air. The best a HEPA could do is filter 1% more.
 
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Out gassing humans in the cabin, along with dust mites, chiggers, and finer media, probably has something to do with it.
 
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I just checked the cabin filter last weekend on my stang for the 1st time last weekend. It really wasn't too bad. I guess thats because I usually just crack the passenger side window instead of turning on the air/heat I just like the "fresh air" a little better. It could have easily been replaced but i just tapped it out and pulled out a couple of small leaves and replaced it. My guess as to why some of them are dirtier is because an engine air filter is contained within a box that is designed not to allow in foreign debris whereas on my Stang at least the filter is in a place where leaves and other stuff could easily find their way into.
 
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I betcha cabin filters get so dirty so fast is because, like in my Volvo, the car has a cabin pollution sensor which can take control of the air conditioning system and choose if air should be inducted from outside or the cabin air is dirty enough to clean it instead. So maybe the people's filters that are getting so dirty so quickly should stop smoking in their cars, or flatulating. :D
 

Chris Meutsch

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 Originally Posted By: MarkC
Even though you may think an engine air filter is clean after 20-30K, a very wise man who knows about such things recommends that you change it every 10k.
...and I use this wise man's advice for my friends' Honda V-6's.
 

Chris Meutsch

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 Originally Posted By: Hethaerto
I betcha cabin filters get so dirty so fast is because, like in my Volvo, the car has a cabin pollution sensor which can take control of the air conditioning system and choose if air should be inducted from outside or the cabin air is dirty enough to clean it instead. So maybe the people's filters that are getting so dirty so quickly should stop smoking in their cars, or flatulating. :D
I only do outside air, never the recirc. I get moths, leaves, crud, etc. in mine. I can't see the flatulence however.
 
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My engine air filter draws air up. So, gravity makes a good pre-filter. My cabin airfilter will clog up after a few weeks even if I NEVER used the HVAC fan. It seems that every spec of dust, leaf, sand, seed, .... just builds up on it. Them enginsneers aren't thinking too much about location of the cabin air filter's inlet. It also doesn't help that Tom is fat and lazy and doesn't do anything to keep Jerry from building those nests under the hood. Need to cut back on the cat food.
 
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 Originally Posted By: toytundranator
A bit off topic but it sucks for some guys who dont have an cabin AF, like my Tundra and 4Runner.
Nasty! Maybe we need a cabin filter mod for early Tundras.
 
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Chris Meutsch

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 Originally Posted By: toytundranator
A bit off topic but it sucks for some guys who dont have an cabin AF, like my Tundra and 4Runner.
1. Who removes an evap? I guess you, since you otherwise wouldn't have AC! 2. That makes me want to remove mine......but it will never happen due to the labor. Filthy!
 
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 Originally Posted By: XS650
I think a lot less air flows through the average automotive air cleaner than does through the evaporator side of the AC system. If you figure an average horsepower output of a car engine at 40 hp for the life of an air cleaner (that's probably higher then average), that's an average of about 60 cfm airflow. I think the passenger compartment blower moves a lot more air than that.
I completely agree. Do you have a ballpark CFM figure for an average AC unit set on high?
 
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I couldn't find any. Computer case fans run about 50 to 100 cfm and don't begin to compare with a car AC on high fan speed for air flow.
 
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So it's possible with the AC on high you could be pushing more CFM than your average 250hp engine at full throttle... The average CFM should be a lot higher for the cabin filter.
 
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