venting system behind dashboard

Perhaps try removing the fan blower motor first ans see if you are lucky enough that he got trapped there or any where you can see from there. The fan blower is at the foot well in the passenger compartment under the glove box three screws securing it to the under side of the heater housing, very easy to remove.

you need to remove dash panel completely and remove case and ducts. about an 8 hour job at a shop. Roy