It could actually be a few different problems. The most common problem is a broken vacuum line to the actuator or
the tee or the hose going back to the dump switch above the brake pedal.
Other problems need to be traced wire by wire with the electrical
troubleshooting manual. Common problem is probably bad wires to the
If you need a free wiring diagram for your Aerostar please submit all your information here
and we will be glad to send you what ever assistance we can. Will defininately send you the vacuum hose explosion and wiring diagram, free of charge.