Alright, here's my dilemma. We installed factory air conditioning on our 1967 Mustang. Just yesterday we got the compressor to blow cold air after we charged the system with R-134a. Don't worry, we evacuated the system of freon and oil and replaced the ac dryer, so it is a legitimate conversion. The only issue we have left is we cannot get the vacuum switch in the dash to operate and control the vacuum advances. I installed the vacuum lines into the car as was charted on the diagrams I found on the computer and we believe they are correct after double and triple checking. My question to you guys is: on all of the diagrams, the vacuum line going to the engine vacuum source is not clear as to what source to use, so where is the right place to put this vacuum line? Right now we have the vacuum line going to the back of the Edelbrock 650cfm carburetor we installed. We needed to remove an allen-headed plug and put a port in to use it. One of our friends suggested connecting the line in a T fitting to where the automatic transmission vacuum is on the intake. Any suggestions on where the best vacuum is to use for the ac?

 

Update: we now have adequate vacuum from the port on the intake but the switch still does not work. How often do these ac vent control switches go bad, because I do not see all four of the vacuum advances going bad at the same time?