cleaning

1993 Ford Ranger has been sitting on a farm for 4+ years. I cleaned everything I could get to but when the heater is used, I can smell rancid mouse urine. How can I get into the air ducts or cowl to clean and sanitize it?

Anybody have any experience/tips or tricks cleaning them? Thinking about taking it off and maybe soaking and pressure washing it. I have a some minimal experience working on my own truck but am no mechanic. I just dumped a good bit of money into my ranger with a good ol’ boy mechanic just to...