I have a 1995 Ford Windstar. When the van sits in the hot sun for a couple of hours, the door ajar light comes on and the alarm goes off until I accelerate to 15 mph. This makes it difficult to drive in the city, because at every stop light the alarm sounds.
I took the van in twice, under warranty, and the dealer could find nothing wrong. I took it in a third time to a different dealer who charged me $85 for an electrical check, and could find nothing wrong.
We have learned to park the van in the shade when possible, but would like to fix it.
My first suggestion is to dig up the receipts from the dealer who failed to find the problem while the vehicle was still under the manufacturer's warranty. Then make a B-line back to that service department with the receipts in one hand, and Ford Technical Service Bulletin number 95-2-9 in the other.
This TSB was released in January of 1995, and was probably overlooked when you were in with the problem. Even though your warranty has expired, the dealer and Ford Motor Company should still make the repair at no charge. This is common practice as long as you have the complaint documented during the warranty period.
The service bulletin involves an internal failure of the contact terminal assembly located inside the van's sliding door. This will cause a false illumination of the dome lamp and door ajar warning lamp, or a false door chime, or anti-theft activation.
The fix is a fairly involved procedure which requires the replacement of the sliding door switch "contact terminal assembly plate" in the B-Pillar, and the "plunger contact terminal assembly" in the door itself. Once the job is completed, you can park wherever you want.