Cure for the mouse problem

Maybe if it is spiked with something that tastes horrible to them. Otherwise, no way.

Rats are even worse, they tunneled into our attic from the roof by chewing through the stucco under the eves. They also worked their way down the inside of a wall from there and tore out the stucco around the garage sink drain. The roof problem was resolved by nailing metal flashing into that location - rats can chew through a lot, but not steel sheet. I did use some foam to fill up the hole around the drain after placing several layers of strong metal mesh there too. The foam expanded on both sides of the mesh. Followed that with a very unpleasant week of servicing rat traps containing severely injured but not dead rats. (The rat traps killed the two adults as advertised, but only maimed the juveniles. It was really disgusting.) No more rat problems since. Not that I don't expect them to find another way in at some point.

 

I've been fighting this fight for many years. I blocked the holes under the front cowling with hardware cloth as well as the louvered rear vents. I've tried repeatedly applying peppermint oil to the cabin air filter (helps for a little while), and also added hardware cloth to the bottom of the cabin air filter tray.

They were still getting in. The hardware cloth below the wiper cowling up front doesn't stop all of them because there is still another way into the space behind it (possibly via the passenger side wheel well).

Upon further inspection of the cabin air filter area, I discovered they had chewed a hole through the plastic next to the damper, so they were getting in and out without having to penetrate the cabin air filter. I think I've FINALLY found a solution. I removed the blower motor below the cabin air filter and stuffed the better part of 2 rolls of stainless steel mesh into the air intake, pushing some into the gaps on each side as well as filling the space in between. The mesh shouldn't block the air flow too badly since it is air permeable, but the mice don't seem to want to deal with it.

I hope this helps someone else still trying to deal with this issue.

Looking at the cabin air filter assembly


Hole above cabin air filter that mice chewed through plastic


Blower motor removed for access from below cabin air filter assembly.



View of air intake stuffed with stainless steel mesh (camera looking in from cabin air filter slot)

 

While it may be 'permeable', that kinda looks like it would increase airflow resistance more than a bit.

 

@thetuningspoon, are you saying there's a cabin egress at the front of the car (excluding the rear exit vent opening at the corners of the hatch) other than the business-letter sized opening in the firewall?

Addendum, happened to stumble on some pics I posted some years back, here:

Mouse problem | PriusChat

 

I'm sure it will, but I'm getting desperate here!

I'm doubtful it will be an issue. The air is already passing through the cabin air filter, after all. The bigger concern might be debris getting caught in the mesh and blocking the air flow over time. So far I haven't noticed any difference in the blower performance.

Looks like your photos are from a gen 3 so I'm not sure how they compare. The business-letter sized opening in the firewall is the one that I've stuffed here. On the gen 2 that opening is actually behind the openings that Solman636 shows screened off in his post. It is very difficult to access it and screen it off from the outside. Just screening off the outer ones isn't enough, at least for the smarter mice in my locale.