Rodents in hvac

[kenny78]

1982 with ac. I know I should just poke around, but I am sure some of y'all will know exactly where to screen off to eliminate them entering the vents.

Is it an inlet underneath the cowl?

 

[da_raabi]

I would think the only place they could get in is through the cowl, but that is blocked off by the metal grating. Do you have any rust holes in the rockers or around the forward cab body mounts?

I can think of only two holes in the air intake system that would be open to the world. The cowl is the biggest, and that should be covered by the large metal grate that goes between the hood and the windshield; the hole for the blower motor would be the second one, and that should be filled with blower motor. So I'm thinking the rodents must be coming up through a rust hole in your rockers or something. Let us know if you figure it out!

 

[1987 GMC Jimmy]

I've seen quite a few squares with that duct piece going to the driver side vent removed. Is that installed on yours? I'd follow the ductwork in the cab to make sure it's all tightly joined and there aren't any gaps for even a mouse to squeeze through. They can compress their bodies into pretty small places.