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Mouse nest in cabin air filter

Discussion in 'Prime Care, Maintenance and Troubleshooting' started by yaun, Oct 11, 2020.

  1. yaun

    yaun Member

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    I had a mouse nest in my cabin air filter. I first noticed a smell of death 3 days ago and then found a tiny and hairless dead baby mouse in the passenger foot area. I first thought that it must have gotten tracked in through the shoe's profile somehow, but the smell got stronger. Today I opened the cabin filter and there was a nest with a dead mother mouse.

    A couple of questions:

    1) The smell is still not entirely gone. There may be more dead babies somewhere, possibly in the large white container below the air filter, where I can't look into. There are a couple of screws at the front of that container. Can this be taken off easily, or should I bring it to a shop?

    2) How did the mice get in there? Aren't there any meshes in the air inlets that prevent critters from crawling through the venting system into the car? Is there anything that can be done to prevent a repetition of this?

    Picture of the nest in the filter is below. Don't enlarge if you have weak stomach.
    IMG_20201011_161720841_2.jpg
     
    #1 yaun, Oct 11, 2020
    Last edited: Oct 11, 2020
  2. Salamander_King

    Salamander_King Senior Member

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    I don't know the answer to your first question. Others, especially @Elektroingenieur might be able to help you with the exact process for removing that piece.

    As for the second question, refer to this thread: Big trouble! Is mouse-proofing the Prime / Gen 4? different? | PriusChat.

    I have not done it myself, but there are several potential openings that lead to the HVAC duct to the interior of the car. You can also refer to this thread: MouseProofing the Prius | Page 3 | PriusChat However, since it is for earlier generation Prius, some point of entry may be different in the Prius Prime.

    That being said, more of the problem often caused by rodent nesting is not the interior damage or smell but in the engine compartment where they will chew and damage the cable and electrical harnesses rendering your car inoperable and costing $$$ for repair. For that, I don't think there is any good way to close all the entry points. You may have to use rodent repellent or park your car in a rodent-proof garage. In my case, I just use an organic solution by keeping many feral cats always around my car. My wife takes care of TNR cats outside of our house. So far it has worked but with COVID-19, my car is parked longer on my driveway without being driven. I may have to look into doing something on my car.
     
    #2 Salamander_King, Oct 11, 2020
    Last edited: Oct 11, 2020
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  3. bisco

    bisco cookie crumbler

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    they usually get in if the car sits for awhile. i put baking soda on the cabin filter. as to how they get in, it's complicated, but easy.
     
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  4. Elektroingenieur

    Elektroingenieur Senior Member

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    The large white part is the blower assembly, and—at least according to the Repair Manual (more info)—it comes out only as part of the air conditioner unit assembly. Removing this is a major job that requires disassembling the entire instrument panel and recovering the refrigerant. The two screws seen below the air filter opening attach the lower instrument panel sub-assembly and the No. 2 air duct, neither of which can be removed on its own.

    You can get some access inside the blower assembly without removing it from the car, however. The blower motor with fan sub-assembly can be removed from the bottom, after first removing only the No. 2 instrument panel under cover sub-assembly. See parts catalog Figure 87-14, Heating & Air Conditioning – Cooler Unit, in which the fan sub-assembly has part name code 87103B. It’s held in place with three screws; see the Repair Manual under Vehicle Interior: Heating/Air Conditioning: Front Blower Motor for procedures.
     
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  5. yaun

    yaun Member

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    Thanks for the comments. I ordered a borescope and will have a look into the blower assembly and other parts of venting tubes before I decide if I clean up myself or bring it to a shop.

    If I set the climate control to 'recycle air' before I shut down the car, will the path from the outside to the cabin filter be closed?
     
  6. Tips

    Tips Member

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    Why do you add baking soda onto the cabin air filter? , Bicso.

    Posted via the PriusChat mobile app.
     
  7. Tips

    Tips Member

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  8. Tips

    Tips Member

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  9. Salamander_King

    Salamander_King Senior Member

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    Baking soda is often used as a deodorizing agent. Remove the dead animal smells. There are aftermarket cabin air filters that come with baking soda already applied to it.

    upload_2020-10-11_22-44-15.png
     
    #9 Salamander_King, Oct 11, 2020
    Last edited: Oct 11, 2020
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  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Not sure, but I doubt it. I would put 1/4" rodent mesh over the cabin air intake. Probably you'll need to remove the wipers, associated motor and windshield cowl. Also good to put the same mesh over the engine air intake.
     
  11. Elektroingenieur

    Elektroingenieur Senior Member

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    Not usually. The filter is downstream of the air inlet control damper, as on fourth-generation Prius cars, but as the Repair Manual mentions, there is a “Parking Fresh Control” feature: “When 60 seconds have elapsed since the power switch has been turned off, the air conditioning amplifier assembly uses control logic which automatically changes the air inlet to FRESH mode to purge undesired odors from the air conditioning unit.” The RECIRCULATION mode is restored when the car is started.

    I believe this feature can be disabled, however, by using a Toyota Techstream diagnostic system to change the “Outside Air Mode Auto Switch Function” customize parameter from ON (the default) to OFF.
     
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  12. Salamander_King

    Salamander_King Senior Member

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    I think that feature is also customizable using Carista.

    Open vents to outside air when ignition is turned off: default is YES, but can be changed to NO

    upload_2020-10-11_23-5-32.png
     
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  13. xliderider

    xliderider Senior Member

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    I recommend you Google Hanta virus. If you are a hypochondriac, you'll immediately start to to notice symptoms.

    Posted via the PriusChat mobile app.
     
  14. yaun

    yaun Member

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    Great, the symptoms are so similar to Covid, I could kill two birds with one hypochondric stone.
     
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  15. yaun

    yaun Member

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    Toyota did indeed put a mesh at the upper left above the cabin filter which I assume is the venting inlet.

    But it's not metal, it's plastic...


    IMG_004.JPG
     
    #15 yaun, Oct 12, 2020
    Last edited: Oct 12, 2020
  16. bisco

    bisco cookie crumbler

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    ouch, jail break. someone must have smuggled a file in with a birthday cake
     
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  17. bisco

    bisco cookie crumbler

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    it helps to eliminate the odor of decaying mouse. i couldn't find the corpse, but at least the smell is gone.
    then i installed a new charcoal filter.
     
  18. roam92

    roam92 Junior Member

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    I believe I found a simple solution to the mouse problem – an answer that doesn't involve efforts to add physical obstructions to keep rodents out.

    I came to this because it was getting so bad that during the winter that I would have to change the cabin air filter once every few weeks because the mice would keep making a nest in there. It goes without saying that this hindered comfortable use of the car's ventilation system as well.

    Then I was reading somewhere how mice don't like certain scents, and go out of their way to avoid particular smells. One of the smells the article mentioned was peppermint.

    So, I had an idea – to try to defeat the mice another way. I replaced the cabin air filter yet again, but this time I first lightly saturated the filter with... peppermint essential oil.

    The result was startling. No mice have come in since, for the rest of the winter and all the time since. Six months now, and no mice!

    Since then, I've resprinkled the essential oil on the air filter a couple of times to refresh the smell, but there have been no more nests and I haven't had to replace the filter – it looks as good as the day I installed it.

    Yes, the inside of the car does smell rather like fresh peppermint, but it's a scent – and experience – I enjoy much more than the mice!

    Hope this helps someone else. Much easier I think than trying to block them.
     
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  19. Mendel Leisk

    Mendel Leisk Senior Member

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    There’s an air intake below the wiper linkage and cowl. Putting 1/4” galvanized steel mesh over it does the trick.

    good idea to mesh the engine air intake snorkel too.
     
  20. Salamander_King

    Salamander_King Senior Member

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    I was reminded again by my own comment, how lucky I have been for the last 30+ years for not having to deal with rodent infestation in my vehicles. That is until about 2 weeks ago. Here is my own account of how I am dealing with the ongoing mouse problem.

    Mouse nesting locations in the Prius Prime | PriusChat

    To summarize, no repellents tested so far, including peppermint, are effective. And blocking the mouse from entering the cabin space alone can not solve the bigger problem of the mouse entering the engine bay (and potentially causing major damage to the car). To deal with a rodent pest problem, it must be dealt with in a wider area with integrated pest management (IPM) principal of 1. exclusion, 2. habitat modification, and 3. population control.
     
    #20 Salamander_King, May 12, 2022
    Last edited: May 12, 2022