3-Way Solenoid
This electro-vacuum valve has connections from intake manifold vacuum and to servo diaphragm. Solenoid portion is energized by electrical connections to engine speed switch (air conditioning relay on models so equipped) and ignition switch. As engine speed switch senses engine RPM within operating range, it will open 3-way solenoid to allow passage of intake manifold vacuum which positions servo diaphragm. This causes throttle plate to open slightly.
NOTE:
On models with air conditioning, the air conditioning relay is in-line ahead of engine speed switch. Whenever A/C is in "ON" position, this relay will activate throttle positioner system, allowing slightly higher idle speeds.