Thanks for the advice everyone. I will try a few of your suggestions when it warms up again. We went from 83 degrees to freezing and snow within a couple days here. Gotta love that Midwest weather. To Lupdiesel, If the box is clogged, it's probably not a mouse problem. When I bought the car it was pulled out into the driveway and I noticed dead roaches everywhere. The seller said the neighbors had a problem and had just had their house exterminated. I discovered it wasn't the neighbors. After bringing the car home it sat on a car trailer for a couple days and I checked it for hitchhikers and didn't find anything. After putting it in my garage, they started showing up. It took several attempts to exterminate them. Not trying to gross anyone out but you never know what's living in that next project car. I should have put a tarp over it and bug bombed it before bringing it in.
Thanks again---Brian