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Cabin air filter & air flow direction

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by jackmaster, Nov 23, 2008.

  1. jackmaster

    jackmaster Junior Member

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    Kragen just sold me a Bosch P3785 cabin air filter for my 2005 Prius. This particular filter isn't shaped like the OEM filter in that it's not clear which way is up; the filter is symetric on top and bottom. On the side of the Bosch filter, there's an arrow showing the air flow direction.

    Does anyone know the air flow direction for the 2005 Prius cabin air filter? Does the air flow from the bottom to the top, or from the top to the bottom of the filter? Thanks!

    Rob
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Top to bottom IIRC.
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Top to bottom; the proof is that the dirt and leaves accumulate on top of a used cabin air filter.
     
  4. bulldog

    bulldog Member

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    Great filter. I have been using it for sometime in my offroad vehicle as well. They filter so much netter than the OEM, and cost the same or less. You can also clean the filter with compressed air to extend the life for quite some time.


    As others have said flow is top to bottom.
     
  5. teronimus

    teronimus New Member

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    I have viewed several discussions on this question which way does the air flow in the Prius blower housing. I am now more confused than ever so that I will just have to evaluate my Prius. Arrow points up in the direction of the air flow. Others claim that debris is collecting on the top of the filter. Viewing my filter with what appears to be the dirty side is the top but the air flow directionds shows upwards. Answer to come later. Unfortunately who knows how many Prius configurations there are?
     
  6. dolj

    dolj Senior Member

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    The arrows indicate the orientation of the filter for installation, not the direction of the airflow.

    As stated above in several posts, airflows from top to bottom.

    The filter is installed with the arrows pointing upwards.
     
  7. ChapmanF

    ChapmanF Senior Member

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    The wrinkle in the original post was that some aftermarket filters are marked with an airflow direction arrow, in contrast to the Toyota filters, which are marked with an up arrow.

    So the first thing anybody needs to figure out is, does this new filter I am looking at have an up arrow, or a flow arrow?

    If it's an up arrow, install it pointing up. If it's a flow arrow, install it pointing down.
     
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  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Is the only issue here, to ensure that after some use, the filter is not removed, and (inadvertantly) flipped over before reinstall?

    If the filter appears to be symmetrical faced, I'd just mark the front edge with an arrow saying "this side up", or "this side down", and install that way. If the filter already says something like that, prominently, follow it.

    Too, cabin filters didn't exist, a few decades back. I rank them with dryer sheets.
     
  9. ChapmanF

    ChapmanF Senior Member

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    Ah, those were the days. Back when the autumn leaves would get finely mulched by the blower wheel and then packed tightly under air pressure between all the evaporator fins, which you'd have to take the dash apart to clean out.

    I had an evaporator soaking for a few days once in a wastebasket filled with warm water and some of those digestive enzymes you buy to pour in a septic system. That turned all the packed leaf powder into glop, which could then be flushed out with the pressure wand at the car wash. A pretty successful operation, all told.
     
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