I am just about done with my 71 s. The only thing I haven't done is the ac. I have a question. I know the car has a vacuum ball on firewall and a ported vacuum actuated switch on the intake. I would like to know what these items do and how crucial they are to the operation of the ac. Thanks in advance.

Leche

Also if possible does anyone have a diagram of all the vacuum lines and where they are routed etc?

thanks

 

I don't know if this will help. I wasn't sure if you meant the general vacuum diagram, or just for the A/C. This is the general setup for the 350 and the 455 from the 1971 Service Manual. Hope it helps.

 

thanks. I believe that is exactly what I need.

 

Once again, GM is not in the habit of adding parts to a car that are not necessary.

In the case of the vacuum ball, it's a reservoir with a check valve, similar to the power brake booster. The flapper doors inside the A/C box under the dash are vacuum actuated. At wide open throttle, manifold vacuum goes to zero and all these doors would move from the position you have them set at to the default position (usually defrost). That means that in the summer if you had cold air coming out the dash vents, during W.O.T. it would switch to the defroster vents. The vacuum ball provides a vacuum reserve so that during W.O.T. periods the flapper doors stay where you want them.

It doesn't hurt performance in any way, so there's no reason to remove it. If you are trying to clean up the firewall, simply mount the ball someplace else (under the fender, for example) and run longer hoses.