get a big mean hungry cat.

 

X2...
Had a rescue cat once...it was a stray so it loved to be outside, built it a small home outside...kept water and food handy but let me tell you this, no mouse, chipmonk, bird or other small animal was safe around the house for years....I now have a rescue border collie, this dang dog protects her "flock" (my wife, the kids and then me-in that order) first and asks questions later . Once had to get a different home health nurse for the wife because the dog would not let the one we got near my wife without trying to protect my wife....got a new nurse, kept the dog.

Anyway back to the task. I think, been years, you can pull the center vent and "snake" a hose to the "other side" of the evap/heater core thru there and use a shop vac to clean things out, if it is not on the "blower" side of things.

 

OK just in case any of these pictures helps...

 

Thanks for that diagram but I found one at the top of the diy section and did that with a shop vac yesterday and stuck my hand in there feeling for somethin found nothin but debris. I downloaded the whole shop manual and have been skimming through it since. Lots of good stuff especially all the vacuum lines. There are so many.

As for a cat I can't now till my old dog dies. He is sick and the stress of a cat would drive him to a quicker death. He sees a squirrel gets excited and has a siezure vet says he doesn't have a long time. He's got cancer.

 

Thanks for the info too.