vaccuum lines

I had alot of cooling problems and changed radiator,heater valve, heater hose etc, that problem solved but I have a vaccuum line off and would like to know if anybody would have a diagram of the vaccuum lines it is coming off the a/c system its the large line coming out of the tee by the firewall also I now have the does not crank mystery

See 91 astro vacuum problems. igw

I also had the brittle lines and changed them last year.The line that is loose is the large line going down not the one to the engine I think it might control the door for the heater