Ok I Now Need Help 69 Riviera

I Have A 1969 Buick Riviera And Im Trying To Fix The A/c This Car Has The Ac Unit And Everthing Seems To Be In The Right Place But No One Ca N Find Out Why It Dont Work Is There Any Tricks To This A/c If There Us Anyone Out There That Can Help Please Write Back To Me Are You Can Pm Me
Thanks