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When I investigated a slight "damp leaves" aroma in my '08 Civic and pulled the cabin air filter, I found some debris (leaf pieces, maple seeds) on the top of the filter, and what looks like chewing marks. I've edited this post now that I looked closer - top of filter has mouse turds and probably urine stains. Feh.


The big surprise was that below the filter and on top of the blower blades, was a big pile of debris, also what looked like shredded kleenex (this is after I reached in and pulled out most of it):


It even looks like some of the blower vanes have been chewed. WTF. I'm baffled how this crap got into that space, and apparently got past the filter. I would appreciate any advice on how to track down the problem and fix it.

You probably already figured this car does not have a garage, and there are plenty of rodents around.

Thanks!

 
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The hard part is figuring WHERE their entering, and doing something to prevent it.

 
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They are entering through the cabin filter. DUH!

If the meeces only got as far as the fan, that's great.

I bet a crafty person could remove the cowl panels and fabricate a wire mesh of some sort over the HVAC opening to block critters.

 
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.....and then electrify it.

 
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don't worry too much, get to an exhaust shop and have them installe the CAT inside the car, it will drive the mice out
like said above, cabin filter?

 
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How to test your engine valves:

Install cheese inside the tailpipe
Insert mouse into air filter box.
Wait.
If the mouse reaches the cheese at the tailpipe, you have bad valves.

 
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Thanks guys for the replies, and the humor Now I know why it's a CATalytic converter.

But seriously...the outside air intake seems to be a strip of black plastic, just below windshield, perforated with about 1/4" holes. If there's another intake large enough for a mouse, I'd appreciate info on where it is. In the meantime I've replaced the disgusting cabin air filter and will wire on top of it, a rectangle of 1/4" hardware cloth. Try chewing thru that, suckers!

 
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What do you see looking through that opening ?? I swear it looks open (I saw bolts) would think there would be some ducting to it but maybe not.

 
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No, that's the cowl cover panel. Remove it to find the blower intake area inside. The cowl area is huge, the wiper motor and linkages are all in there too.

 
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We had a similar problem with our 2006 Civic EX but the mice were also running around inside the car, chewing on items like the seat belts and nesting in the trunk spare tire well. The only place I could find where they might have been getting in was the fresh air intake ductwork. We decided to always place the air handler in ‘recirc’ mode to block their access but it didn’t take them long to chew thru the recirc door.

If you look at the fresh air input from the outside, thru the black cowl cover, you will see that the opening has no screen over it. The cowl cover keeps things like leaves from entering but mice can get into that area by crawling thru the opening for the hood hinges.

I removed the black plastic cowl cover with the intent of installing wire mesh but it was impossible to get that far into the cowl. I then removed the entire blower motor housing which gave me access to the inside of the firewall. I installed thick mesh screening, on the inside, then reinstalled the blower motor housing. We have not had a mouse inside the car since.

 
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How big of a job was that ??

Thanks for the info.

 
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It wasn't too bad. There are a couple of screws way in the back that I had to use a mirror and flashlight to find. I did not remove the blower fan, it stayed mounted in the housing. Unfortunately I did not take any pictures of the procedure at the time but I just took these that show where the problem was and the type of mesh used.

 
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^^^ Thanks, I will check out the manual and see if I can find procedure.

Glad you got it stopped, may want to consider doing your air intake opening as well

 
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Thanks for the suggestion. I just looked under the air filter and while there was no mouse droppings there was some debris that probably didn't get there naturally. It looks like there is an air inlet port in the rear of the intake box as well as the front.

 
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I have had leaves and whirly gigs get into my air intake, but not past filter though. Was not aware of additional openings in housing.

The oval shaped mesh screen in the photos....? is that what you added ???

 
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Yes but it only looks oval because the opening in the firewall is oval. The piece of mesh I added was rectangular. I screwed it to the firewall so it would stay in place. The blower box had foam around the area that mates to the firewall so it just compressed up against the mesh.

 
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Good info, thanks for sharing with us.

 
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You're welcome, glad I could reciprocate. Last week I learned from this forum how to change tranny fluid and also answered my questions about timing belt vs timing chain.

 
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It's an old thread but not an old problem. I built a home for my mother-in-law at our farm. She seldom drives and parks next to a wooded area. Anyhow, she complained of a stench in her 2008 civic. Upon investigation I found a tremendous amount of debris and a dead mouse in the cabin filter area. It was cleared and the filter replaced. Over the next few weeks I discovered more debris, mostly jute from the car, blocking the new cabin filter. The mice had started chewing the filter too! Today I removed the cowl (A1Auto has a great video) and removed the wiper assembly to gain full access. The fresh air intake is wide open, 9" x 5", allowing the mice to easily get in after climbing around the plastic cowl. I made a template and cut a grate from a piece of SS perforated sheet. Four nutserts were fitted and I installed it in the intake hole. I don't know if a mouse is still in the ventilation ducting but I know it can't get out. Heading to the store to replace the pee stained filter and hopefully an end to this dilemma.

 
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Nice fix