Does anyone happen to have a color coded vacuum diagram for a 1990 Bronco/F-150 that they could post? I have a loose vacuum line behind the dash and I cannot for the life of me figure out where it goes. It's black, and apparently plugs in somewhere behind the glovebox, but I do not see any place for it. I've looked at all the pictures I took when I took the dash out, but don't see anywhere in them as to where it might have hooked up.

 

1990 vacuum diagram:
Heater only:


Heater+AC:


/

 

Thanks for posting that. Unfortunatly I don't see the vacuum line I'm looking at shown on the diagram. (or maybe I'm just an idiot)
Is there anything else behind the dash that might be vacuum controlled besides the HVAC system?

Since I do not have a picture handy (and uploading pictures on here always causes me problems anyway) I will try to explain what I have based off the diagram above.
Behind the glovebox there is a vacuum connection with 1 white line, and 2 black lines. The white line goes thru the firewall to the outside air door control valve. The one black line goes thru the firewall and connects to the "T", then goes on to the vacuum tree on the manifold. The second black line does NOT go thru the firewall, this is the line I cannot find where it connects to.

 

One of the black lines goes to the vacuum control on the dash. The other end of this line is the one going to the Tee in the engine compartment.

No there is nothing else that uses vacuum under the dash other than the HVAC system.

If this black line is rubber maybe someone had a vacuum gauge mounted on the dash at sometime in the past.

 

Ok, so I guess I am an idiot after all lol.

After studying the vacuum diagram last night I came to an interesting conclusion, one that I confirmed this afternoon after taking a second look at the truck. I guess I got so wrapped up in trying to figure out where the loose connection went, I failed to realize that there is no line for this on the other side of the junction. So the line literally goes no where on either end.

It has to be an OE line, it looks just like every other vacuum line on the truck, so what was it for? The other question I now have is, why did Ford use a 3 port connection if it only connects 2 lines? Guess the guy at the factory responsible for installing the vacuum lines wanted to mess with our minds a little. Oh well. To save future confusion I pulled the line out of the connector and tossed it in the spare parts drawer of my tool box.

Thanks for the help subford. Man do I feel like a dumb@$$ now!

 

Have converted 5.8 efi to carburetor .while cutting down wiring harness to what i needed i know realized i need to have power to the solenoids for my ac to work anybody have an idea on how to trace them down or a diagram that would help. Thanks