Might be stuck from moisture and corrosion. Not familiar with the soft
underbelly of the Aerostar but you might be able to get your head under
the radiator/front bumper area and get a good shot at lubing it with
some liquid wrench or wd-40. Try to work the mechanism free with your
hand or tap it lightly with a small hammer.
Had this happen on my old Escort. Once you get it free put some white
grease spray on the latch mechanism once in a while. Do your door