Packard Forum Index » V-8 (1955-56)

I believe the way these work is vacuum is connected thru solenoid valve to single port on side of extra block and is there at all times. When button pushed, solenoid allows vacuum also into large piston and it draws up a charge of water. When button released, solenoid stops vacuum to piston and spring pushes water which goes thru a chamber in bottom of block. It moves a flapper so vacuum is now applied to co-ordinator and starts WS wiper. As long as water flows, or there is pressure against flapper, vacuum keeps co-ordinator retracted and in operation. As soon as water stops, flapper cuts off vacuum again to co-ordinator and the air bleed via adjust screw slowly allows spring to return it and stop motor.