sliding cargo door on aerostar will not open?

Answer 1

Aerostar... I have a couple of those.

The earliest ones may have the hinges / rails come out of alignment. If that's the case, you can try lubing the rails a bit, but the only real way to fix it is replace the rails and all those wheels/bearings and stuff that goes inside the rails. Those are bent from all the abuse they got with slamming doors and such.

Another possibility is the linkage from handle to actual lock release is broken. You'll have to remove inside panel to see if that is indeed the case. Linkage itself should be pretty cheap.