[hdff]

Originally Posted by snipescastle2

Good info for sure! I know there are two versions of the vacuum control switch (A/C control panel) three ports -vs. two ports,I believe the three port version eliminates the need for a "tee" hope this helps.....
Ben

could you explain a little more on the 3 port. I had read that I needed to plug off the 3rdport and tee the second port twice, once to go to the kick panel vent and once to go to the hot water valve before going to the cowl vent. so if I read this right the 3rd port should go directly to the hot water valve eliminating the T in the engine compartment. I have mine hosed like the illustration for the 2 port

Originally Posted by Andy4639

Crank the truck up and put the AC lever in the positions you mention and go around to the valve and see if it's operating by taking the vacuum line loose at each setting. This will tell you what is going on. It could be the valve itself isn't fully shutting off also which is why I install the manual valves.
If your truck has a big cam are very little vacuum it want close all the way.Per drawing vacuum applied closes the water valve so you have to make sure your hooked up correctly to the valve port on the dash assembly also.





Here is the 3 port connections.

the hot water valve is all enclosed so there is nothing really to see other than feel the hoses which they get hot the experiment is over. in this 2nd pic it looks like a 2 port head and is hard to see exactly what is hooked to where. the 2nd port looks like it does directly to the hot water valve and the cowl and kick panel tee into the main vac line from the carb.......
what service manual did you get this 3 port from. I just looked again at my 71 manual and it doesn't show that pic, it shows the top pic