Tiny spongy material

Discussion in 'Gen 3 Prius Main Forum' started by PriusKyle, Apr 23, 2026 at 10:59 PM.

  1. PriusKyle

    PriusKyle Junior Member

    Joined:
    Mar 12, 2022
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    Location:
    Virginia
    Vehicle:
    2011 Prius
    Model:
    Three
    Hi all,
    Not too long ago, I posted regarding my cabin air filter wherevi found small broken pieces of mid gray spongy material in the filter; there was a lot; some suspected there might have been an active mouse infestation (search my posts for cabin air filter if you want) but I never saw any indication beyond small spongy material that ended up in my cabin air filter. I eventually replaced the cabin air filter and used fridgi fresh through the air duct.
    Today when I started the car, and my AC was on full blast, small bits of mid gray spongy material came spewing out of the air vents; they looked very similar to the ones that were mainly intercepted by the cabin air filter.
    What’s going on?
    Do our 3rd gen have some sort of mid gray spongy material lining the duct work within our car and it just was deteriorating, hence bring blown through vent. What do you think is going on with my car? Just old material that’s deteriorating due to age? I also noticed that my air recirculating doesn’t seem to work as well as before as it allows foul odor to come through as though I pressed the fresh button. Several times I experienced what seem like rotten egg smell coming through the vent. Is this a coincidence or do you think there’s a connection
    Does anyone know if there’s gray spongy material that is either in the duct or somewhere else but eventually making its way through the vent.
    What material is it, where’s it located and is it an easy fix?
     

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  2. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
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    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    It might be the standard cheap toyota foam that is part of the HVAC system, but it's also small enough that it could of got sucked in due to a failed screen in the vents as well as places access can be chewed open near where your windshield wipers are. Worse case, you got some mice that found their way in... There's plenty of threads on here about how to rodent proof your HVAC.

    I could probably tell you which of these problems you have if I saw the overall condition of your car... The cars that are never cleaned of old food and sit unused for a long time are heaven to small rodents. I've pulled cabin air filters with so much debris you can barely see the filter. Even once pulled a filter that I could barely get out because there was an emaciated rat that died inside due to the car sitting for years.