We have an '02 Honda Accord 4dr that is parked outside (the model A & Ts get to stay inside) and we have an ongoing problem of mice getting into the heater blower and nesting. This also clogs the cabin filters. And sometimes really stinks up the car! If I knew where the air intake is, I could put some screening over it.
A common solution is stainless steel wool used in the intake to prevent them from getting in, yet allow the air to come in.The air intake is at the base of the windshield. It’s probably easier to reach from under the hood.
There is an air intake grill at the base of the windshield, but I don’t see how mice can get through that. The nesting material appears to be fiberglass insulation, yellow. Is it possible the mice have chewed a hole into the air duct under the hood somewhere??
Install (1) small, barn cat into heating ducts under the dash. No more mouse problem. 
But the cat poo may give the car a whole “new” odor that may not be pleasing to your nose.
Yellow insulation came from your house, get it fumigated. Seal all holes. Buy good traps and bait them. You have to minimize the number of mice in the area. The mice are getting into the car and they are probably getting in through the opening for recycled air and getting to the exercise wheel that blows the air.
They are entering the inlet from under the grill. When you remove it you will see they can crawl up the drain path along the firewall. The grill is only there to stop leaves from above. The fiberglass is from hood or firewall insulation mat they chewed up. I’ve screened off every car I have for the same reason. Works perfectly.
I live on 10 acres in the woods–I am constantly baiting and trying to trap mice & rats. There seems to be an unlimited quantity of these critters! The Cat idea is good, except I’m allergic, and it seems the other animals around here do in any cats I find to try to keep here (or they decide they want to be indoor cats and migrate to the neighbors who let them inside!) As soon as it stops raining, I will see how to remove the grill and inspect the drain hole. BTW, my house is so old there’s no yellow insulation–pink and white though.
“Exercise wheel” HAH!! I like that! But I think it’s more like a horror movie with the big fan ready to chop up the hero!
I’ll let y’all know if I figure it out.
Thanks!
Yes, there is an unlimited supply of them where you live and they will be persistent. It isn’t easy.
He Dodgevan–at least the rattlesnakes haven’t been a problem (YET??? YOICKS!!!) I hear they do eat mice though. . .
I have a house in rural Mexico which is currently mice, rat, and scorpion free. I bought some high powered ultrasonic repellers from Aurrera, a subsidiary of Wal-mart Mexico. People who have never tried them will tell you they don’t work.
The problem is ultrasonic power. We have some tough boxes here, produced by Steren. I have seen a lizard actually stunned and unable to move when getting close to one of these. In the US, you only get very low powered ones from places like Home Depot and Lowes.
Even here, they claim two would do our 2850 square feet house. We had to put in 8 before the pest problems went away. So, I really can’t tell you if the small ones in the US will work. I can tell you their claims that one of those tiny ones in a garage will eliminate all mice is pure nonsense. They might work the foot or so to block access to your ductwork. If nothing else works, it might be worth trying. I also am not sure if it’s a good idea to drive with those cheap electronics under the hood.
The problem is having to plug and unplug every time you park or start the car.
The last time we had this discussion, someone claimed Consumer’s Report said they didn’t work. Such a statement would surprise me, because CR has certain language they use for legal reasons, and normally they would say the product does not meet advertised claims, and I would agree with that because of the preposterous claims for area protected.
I have a number of these units (the US ones) in my garages, and I still find “drops” left by the rodents. I’ve added bait blocks and granules too. I’ve worked on lots of cars, including RR’s, and this vent has me buffaloed. I can see how I think the plastic vent cover comes off, but don’t see how I can reach down to any drain openings. Maybe I can get someone to put it on a lift and find them from underneath? You’d think Honda would have done something about this, if it’s a common problem in rural areas.
Did you read my previous post?
The air inlet is under that grill. Generally, they are constructed as a snorkel so rain water washing down off the windshield will run off the sides of the firewall but not be able to run down into the air intake. This snorkel extends up slightly. Often, you can see it from below if you remove/lower the glovebox, remove the cabin filter and peer up through the inlet from below. It should also be visible from above. I take a section of galvanized window screen and form it over the top of the snorkel. Then secure it with a lenth of bailing wire twisted around the circumference of the snorkel.
I’ve used this approach on Toyota, Chevy, Ford, Mazda and Dodge vehicles in the past. They all had similar construction. The Honda may be different but there’s only so many ways to slice an egg. There has to be an air inlet and it has to have a method for baffling water ingress.
BTW- I also screen off the engine air intake. I’ve found several pounds of acorns inside the air cleaner housing before doing so.