AC water valve

Reinstalling air in my 71 swinger basket case. Got the electrical worked out,now on to vacuum. I think I've got all the vacuum lines on right, except the water valve. The little grommet going thru the fire wall has 2 holes in it. One for the vacuum with no stripe, the vacuum supply, The other with white stripe goes to the water valve. Where does the water valve get the vacuum for the other side of the diaphragm? Do they sneak another line thru the firewall somewhere? Thanks Jim