around the dealership we have used the vanilla tree air fresheners, under the hood to deture mice and rats, if its a pack rat however they just like the taste of em.....
might be worth a try after you eliminate them, as a deturant...
One thing i can say for sure, if you have a pack-rat in your garage, a quick stab with a blow down nozzle (the one with the long pipe to clean the floor) will do amazing things to one, just make sure you turn the air off before.... well you get the picture...
