the picture below is confusing me a bit. the bottom part goes into the cab to the air conditioning stuff, and the top part goes into the vacuum tree. what does the left part go into? im re running all my lines simpler than the way they came from the factory following a write up on fullsizebronco.com.

also is that conector just a tee? or is it a special one way valve or something?

i need to know how to run these last few lines to finish up my truck.

 

The left part goes to the vent system vacuum reservoir.
That "T" is also a check valve.

 

Ok my ac is blowing through my defrost. Actually every setting is just not my defrost. Very very very little is coming out my vents. That means a vacuum leak right?

Also whats a check valve? Is that just a regular "t"?

 

No it lets air go into the engine but does not let it come back out.
That is why there is a vacuum in the vent system when you go WOT.
Yes you have a vacuum leak.

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Thank you. Ive changed all my lines except for the two that go into the cab. Im guessing these are my leakers.

Any tips on trying to get the hose through the rubber grommet on the fire wall?

 

Some good info and pics in this thread from another forum: A/C and/or heater stuck on defrost - FSB Forums

 

well im pretty sure i foudn my problem. i found a vacuum door or actuator. whatever their called under the dash next to the glove box. i turned on my ac and pushed it in and it started blowing out my vents like its supposed to. so im assuming its that blue line that goes to it or could it be that thing itself? anyways the line goes upbehind the dash and im having a bit of trouble tracing its path. i know it eventually plugs into the a/c control panel but before that im not too sure. am i going to have to pull part of the dash off for this one?

 

Noboby know?

 

I do not think the blue vacuum line or the vacuum motor is your problem.











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Why do you say that? What would cause it to blow out the defrost continuously?

 

I have never hear of that blue vacuum line or its Panel Door vacuum motor going bad.
As said above most of the time it is the white vacuum line going to the vacuum motor on top of the heater/AC box that has a break.
But your truck from what I can gather is not getting any vacuum to the vacuum control on the dash. photos and images above in this thread.

No vacuum to selector vacuum valve (vent system).

 

It will default to the defrost vent if vacuum isn't present. I agree with subford. That isn't likely to be the source of the problem.

 

I replaced that white line already but ill check it over and see if theirs any holes in it.

 

I checked it out. Both lines are good. Could it be the thing in the picture above that the white vacuum line plugs into?

 

Yes, if the vacuum reservoir is leaking, it could very well cause your issue.