1975 Formula AC/Heater vacuum line manifold tube placement
 

Hello everyone.
- I am new and was recommended by my "Pontiac Camshaft Guy", Lee Atkinson.
-My son was given his Uncle's original owner 1975 Pontiac Firebird Formula 400.
-We are in the process of putting the car together and I have 4 vaccum tubes from the heater box (Yellow/White/Blue/Brown) and 1 from the engine compartment (Black).
-The tubes are not in the rubber manifold at the heater control unit.
-The control unit has 5 ports labled: 1, 2, 3, 4, 7
-I cannot find any diagram to match the numbers on the manifold to the tube color.
-I appreciate any/all assistance
Attachment 662864

I did a heater core on my 1976 Firebird last winter, and I thought the tubes were all together in one connector making the reconnecting simple. I will try to find some pictures.

Thank you.
Yes, they are all on the manifold, but being a rookie Pontiac guy I didn't realize that it separated from the heater control.

Did you figure this out? I was just looking through my 1976 Factory Assembly Manual and I found a drawing of the vacuum hose diagram.

I have not found any diagrams on the manifold port to tube colors.
Really odd as some of the manifolds sit at the rear of the heater control, while my son's sits facing downward

I have not found any diagrams on the manifold port to tube colors.
Really odd as some of the manifolds sit at the rear of the heater control, while my son's sits facing downward

This is from the 1976 Firebird Factory Assembly Manual.

Thank you. That is the same printout I found for a 1978. I may have to just run air through the manifold and move the lever to see what position corresponds.

1973-6 should be the same, maybe more. Here are the sheets out of the '74 manual. As you can see, doesn't really show how they are mounted on the plastic fitting.

If you;re assembling a car taken apart, you should invest in the assembly manual. Maybe even this one, which has '73 and '74 too, it's just not a hard copy. https://www.ebay.com/itm/405021553554

Thank you, I have invested in that exact manual, but it did not give the same number of tubes.

With the exception of one extra tube on your diagram, to color tube to manifold number is correct!!

I have a good friend, that had a shop, saved all hisold manauls. He had a 5 inch thick manual just for GM/Buick/Olds AC/Heat systems, he found the exact one for my son's car. It was under 1974 because the car was manufactured in 1974, but sold as a 1975.

These cars have LOTS of "moving parts"!!

Thank you so much for the help and posting!!

Here is what one of my '74s had...

PERFECT!!!! Thanks