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Discussion Starter · #1 ·
Hello, I purchased a 71 formula 400 with A/C the heater control vacuum hoses are all unplugged behind the dash,

does anyone have the schematic for the vacuum routing that goes to a 9 port valve, and the 3 port valve attached to

the heater controls? It looks like a mess back there and would like to get it straight. Thank you.
 

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1968 Convertible 400, 200 4R, 1971 Formula 400 M-22 Rock Crusher, 1984 Trans Am...........
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Let me see what I can find. I know at one time I had a copy, lol
 

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Discussion Starter · #3 ·
for the life of me I don't know why it isn't in the service, assembly, or fisher body manuals.

nice Formula by the way. I have a lucern blue, with blue interior, automatic though.
 

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1968 Convertible 400, 200 4R, 1971 Formula 400 M-22 Rock Crusher, 1984 Trans Am...........
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The service manual has A, B & G body's just not F. But between those you can figure out how Firebirds should be hooked up. Just look at the color of the vacuum lines coming from the components, then hook it up to the correct spot on the select lever valve.

Nice to meet another lucy blue formula owner.
 

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Discussion Starter · #5 ·
ok will give it a shot, I didn't look closely at the hoses I thought they were all black will give it another look to see if there are colors on them.
 

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Discussion Starter · #6 ·
hoses have been replaced by someone, no colors. I can put vacuum to the hoses individually and get an idea which doors they activate, but not sure what all the doors do, or what the position of them should be in when all controls or off. very frustrating that F-Body schematics weren't included in the manuals. Can anyone help further? Thanks.
 

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1968 Convertible 400, 200 4R, 1971 Formula 400 M-22 Rock Crusher, 1984 Trans Am...........
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try the 72 manual in the Tech Articles.
 

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Discussion Starter · #8 ·
For Anyone who may need this info for a 71 firebird formula with A/C. Port 1 White, Port 2 Brown, Port 3 Black(Engine Vacuum), port 4 is Blue, Port 5 is Gray which goes to port 2 of 3 port switch, Gray continues from Port 1 of 3 port switch to heater control Valve as long as you don't have a red hose, 6 is open, port 7 is yellow, port 8 open, port 9 open.
 

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For Anyone who may need this info for a 71 firebird formula with A/C. Port 1 White, Port 2 Brown, Port 3 Black(Engine Vacuum), port 4 is Blue, Port 5 is Gray which goes to port 2 of 3 port switch, Gray continues from Port 1 of 3 port switch to heater control Valve as long as you don't have a red hose, 6 is open, port 7 is yellow, port 8 open, port 9 open.
I have a 72 Formula 350 w/AC and have been scouring the internet for a 72 vacuum diagram. Have been using a 78 (5-port switch).

Yesterday I found another (yellow?) vacuum line and don't know where it goes. I have the white, brown, black, blue, gray and now 2

yellow. Sheesh. Will try your hookup and see how that works. Will also determine if my 72 has the secondary vacuum switch for the

heater valve. Of that I don't know. FYI: the port assignements on the 78 diagram are: port 1 open, port 2brown (kick panel), port 3 (black vac source),

port 4 blue defrost, port 5 yellow diverter door, port 6 white AC diverter door. ports 7,8,9, open. My port six goes to the door on the upper cowl

which you can see with the hood up. Ordered an assembly manual, and a electrical/vacuum diagram manual specifically for the 72 model year.

Be interesting to see what that holds. I'm using a "reconditioned" vacuum switch which I'm not sure is totally reconditioned but that jury is still

out. Thanks much for the input. Much appreciated.

Tonino
 

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Discussion Starter · #10 ·
Thank you for adding that info... something I should have done originally, On my 71 the white hose goes to one side of the heater box door valve, Yellow goes to the other side of that same valve, Blue is for the defrost valve, black is engine vacuum, Brown goes to a vacuum T, one end of the T goes to the cowl door, and the other end of the T goes to the passenger kick panel door as an orange hose. Could this extra yellow hose that you have be a faded orange? If it is on the passenger side and too short to go to the heater controls I would think that is where it should go since I don't see you mentioning that you have an orange hose. After dealing with my car I saw a lot of rigging by someone to try to make things happen so I wouldn't be surprised if someone extended your orange hose with a yellow.
An easy way to figure out is to just pull the passenger kick panel and see what color hose you have there.
 

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Layna that's some good info there, especially for the selector positions, but the F bodies are actually simpler and have slightly different colors. Conveniently I am doing a heater core job now so I made note of eveything I took apart. Here is a color coded diagram I made:

70-73%20FBird%20Vacuum.png


Some things to note: The Orange kick panel door line plugs into the Brown cowl line, there is a Y connection above the heater box like Tesla mentioned. Also the White line attaches directly to the diaphragm (firewall side), the Yellow one connects to an elbow that comes out the top of the heater box above the door it controls. This is the only two-way diaphragm on the unit, which is contrary to the A/G body info posted earlier.

This should help both you guys out. All 1970 to 1973s should be the same, with A/C. These vacuum line colors are factory so if yours aren't original and all the same color, you'll have to run vacuum individually to figure what switch position does what. I didn't take the control module apart so I don't know the exact input positions. If the hardware is the same as the A/G body, you can put it together with this diagram and the one Layna provided.
 
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