AC vacuum lines

[Sonny]

Can someone tell me what this “bleed wire” is at the top of this diagram? It’s for a ‘70 Belvedere.

 

[mopar 3 B]

Just a guess. It goes to a intake manifold vac port.

 

[JimKueneman]

My guess is so that after you shut it off it gives the reservoir a little bit of a vent to release the vacuum to pull the recirculation door to the closed position and other doors to the "off" position in a giving amount of time.