Jeep Repair: mice in heater box, floor vents, grand cherokee

Question
I have a 98 Grand Cherokee that mice have claimed as their own. Their smell is delivered by the blower motor.  I even found about 30 acorns in the bottom of the air filter box. I removed a nest from behind the wiper armature and the odor decreased for a while. The nest is still gone, but the smell is back - worse. I removed the blower motor, reached down (with great difficulty) into the bottom of the heater box and found some smelly debris. (How do they get into the duct work and down to the heater box?) I even used a length of garden hose as an extension to my vacuum cleaner to remove the debris. No luck with that. Is there a "quick fix"?  Heater box removal seems like a big job.  Is it possible to remove the bottom part of the heater box without removing most of the dash? How do I prevent this problem in the future?  I hate meeses to pieces!

Answer
I would say they got in either from the floor vents  or via the outside  near the pass side cowl panel. There is a updated screen that u can put in there smaller holes so that stuff does not get in there and clog up the drain. As for getting all the stuff out  the box can be split in half but the dash will need to come out for that to happen. U more then likely have stuff on the other side of the evap where u cant get to.
I do stuff like that here in Atlanta.