Mmmmm any idea how it should be adjusted.The carby has the adjustment screw that sets the idle revs
The correct method of adjustment is to disconnect the solenoid & adjust the base idle screw to around 500 RPM after the engine has fully warmed up.
Then reconnect the solenoid & lift up the throttle lever to allow the solenoid to extend & using a 1/4" spanner adjust the solenoid tip to set the idle speed, which from memory is around 600-700 RPM, depending on whether auto or manual. Then make sure the throttle drops after the ignition is switched off.
Assuming everything is stock & correctly set, the engine will not run-on, after switch off.
This solenoid has nothing to do with the a/cond, all Holden ADR27A carbies (Bendix-Strombergs & Rochester Q-Jets) have this solenoid.