Mice again--cabin air filter

2011 Honda CRV. 2nd spring in a row, acorns and debris on cabin air filter. Has to be mice, probably not enough room for squirrels. Anyway, we’ve replaced the filter again, but are getting sick of it. Last year we were advised to have it set on inside air when parked on the carport–closes a little door they could be getting in. Well, that didn’t help. Any further suggestions? I thought of putting a mousetrap on the pavement under the car…

You could remove the cowling, that strip of metal between the windshield and the hood or the plastic piece that goes from the windshield to under the hood. On the passenger side you will find a short air horn which is the intake for the HVAC outside air. Cover it with an aluminum screen or 1/4" or 3/16" grid hardware cloth. This will keep the mice out.

I lived in the country and had mouse problems, and never found anything that worked except a cat.

Here’s what we use in Minnesota when classic cars/hot rods are stored in unheated pole barns for the winter.

http://www.menards.com/main/outdoors/animal-insect-controls/animal-traps-repellents/messina-wildlifes-rodent-stopper-reg-repellent-32-oz/p-1444439512206-c-10120.htm?tid=3933969395805578292

We just spray around the parimeter of the pole barn and have never had an infestation.

Just spray it around the parimeter of the carport.

Tester

Point is, putting it on inside air closes the intake.
They were getting in some other way.

Putting on intake doesn’t completely close the door.

The vent system will always blend between inside air and outside air.

Tester

OK, I will try the Menard’s stuff, as much as I dislike them.
What does it smell like? It isn’t mint, is it?
Peppermint oil allegedly repels mice.

Keep food out of the car as best you can, and definitely don’t leave any food in the car overnight like peanut butter or any smelly type of food with an odor that would make rodent’s nose twitch with delight. Be sure to roll all the windows up tight whenever parking the car. Rodents can easily get into the hvac system once they get inside of the car. I can’t speak to your car design, but on my Corolla I don’t think there is a way for rodents to get inside the car or into the heating and ventilation systems except through open doors or windows.