New to the forum with a couple ?'s and advice

[Project86]

Originally Posted by Ski-me

Yea, just start replacing vacuum lines as much as you can. Pick up some at a autoparts store and then replace as many as you can/find. I'm sure they are pretty old by now.

Do you hear any air/vacuum noises when you move your HVAC selector around? Like A/C to Norm to Heater to Def? If you don't hear any air type sounds then you need to get your vacuum lines fixed. This will also move your blending door once fixed. Probably need to fix both the vacuum lines and also the blending door tab.

Ok well I remember when I first dropped the motor in and broke it in, a hose hanging from the firewall with a clear looking plug, was touchin the headers and melted. So now I know it's a vacuum source for the system. Didn't know that at all. Now my question is where can I run that vacuum source? All my ports on the carb are used up. And I have a simple fitting on the back of the intake and that's where my brake booster ties into.
That softball canister you were mentioning is on the passenger side on my 86. And vacuum is connected there. Since I don't have a radio I am able to look up into the climate control and see hoses running to a sort of round dial selector for all the vent and def options.

[Project86]

Originally Posted by donut

Not an uh-oh. I'd much rather chase vacuum leaks on this side rather than under the dash.
On my truck (yours may vary), the line ran to a vacuum ''ball", about the size of a softball, on the drivers side (I think location changes on the year.) Then a line ran from that to the engine. I think mine ran to a vacuum "tree" behind the carb.

Basically you just need to get a vacuum source to the firewall pass through. Hopefully, it'll all magically work after that. If not, your good up to a point at least.

So donut that line that passes through the firewall goes to that vacuum ball?

[Project86]

Sorry for triple post but I do remember a canister in the diver side near the gas pedal. To my understanding that is for defrost? Possibly floor boards?

[Ski-me]

Originally Posted by Project86

So donut that line that passes through the firewall goes to that vacuum ball?

Mine is an 89' but I think there is a tee in there that sends a vacuum to the interior via the firewall, and then goes to the HVAC levers/control.

Vacuum comes off EGR valve too, I think.

[Project86]

http://forum.73-87chevytrucks.com/sm...?topic=24841.0
I found a similar post. Post #9 shows a picture and this vacuum line running across the firewall to somewhere in the engine bay. Now on my 86 I have a weird round canister with a 2 wire weather pack plug that is bolted to the firewall wen I first got the truck. The wires seem to run to a bunch of other wire coming from the firewall

[donut]

Here's a post I had bookmarked about the blend doors. http://67-72chevytrucks.com/vboard/s...d.php?t=497477

Feel free to post some pics of what you have questions on, we love pics
Besides, more eyes are always better.

It won't be till the weekend before I can get any.

On mine the line runs from a vacuum "T" on the intake, (behind carb.) to vacuum ball on drivers side firewall. (or not, I broke mine. but it's supposed to go there.) From there to the nipple on the firewall, by the heater box. Cruise, the vacuum setup may be a little different, but bottom line the hvac system needs a vacuum to operate properly.

[Project86]

Originally Posted by donut

Here's a post I had bookmarked about the blend doors. http://67-72chevytrucks.com/vboard/s...d.php?t=497477

Feel free to post some pics of what you have questions on, we love pics
Besides, more eyes are always better.

It won't be till the weekend before I can get any.

On mine the line runs from a vacuum "T" on the intake, (behind carb.) to vacuum ball on drivers side firewall. (or not, I broke mine. but it's supposed to go there.) From there to the nipple on the firewall, by the heater box. Cruise, the vacuum setup may be a little different, but bottom line the hvac system needs a vacuum to operate properly.

So I can put a t fitting on the back of te intake and run a line? AHHHHH so confused. I'm goin to take pictures tomorrow and try to upload. I know that line got melted from the header. So it sounds like I can run it straight from the intake vacuum to where it's located inside the dash

[Project86]

So I found a thirty diagram for the vacuum controls for a/c equipped trucks.
It's not the best but Should help. Can anyone help me pinpoint which line I am needing? I'm thinking the actual vacuum source line

[Project86]

This image follows the previous attached picture I posted

[Ski-me]

So, 45 & 46 look to be your vacuum source. In the first link picture reference, you see a black tube coming out of the firewall, all by itself (left of the wire bundle). There is also some sort of tar sprayed material at that point too. This is your vacuum line that goes from the engine to the AC controls inside.

Follow that tube in the picture, and you see it come into a tee, and then takes off from there (still in the engine compartment area). I think one of the next pieces inline is a check valve. This line then takes off to egr valve/brake booster/carb areas (I think). You just have to follow it. These are the lines you need to replace, one by one.

The second link shows some pictures of the blending door and the mechanisms that control them. Take a look and see if yours is similar and not broken.

Don't know if yours is California, but someone referenced this for an 86' California emissions. Maybe it can help you determine the vacuum line paths better if some of yours are missing.

[Project86]

I'm going to trace that first vacuum line that goes through the firewall and see if I can get it to work

Would all this work with engine off?

[Tx Firefighter]

Originally Posted by Project86

I'm going to trace that first vacuum line that goes through the firewall and see if I can get it to work

Would all this work with engine off?

You have to have vacuum present to operate them. Either by having the engine running and getting vacuum from there, or from a vacuum pump. So, engine not running means no vacuum and nothing vacuum related behind the dash works.

[Project86]

Originally Posted by Tx Firefighter

You have to have vacuum present to operate them. Either by having the engine running and getting vacuum from there, or from a vacuum pump. So, engine not running means no vacuum and nothing vacuum related behind the dash works.

Well that would make sense. But that gives me time to go over everything.
In the process of cleaning out the gas tank

[Tx Firefighter]

Mine is about 30 years older than these, but this is a handy tool for this kind of stuff.

http://www.harborfreight.com/mityvac...ump-39522.html

It comes with all of the various adapters you need to diagnose and work on vacuum stuff. You can also use them to bleed brakes and hydraulic clutch systems. Its a lot better than having the engine sitting there running while you're working, trying to think, and referencing service manuals. You just install the little adapter into your vacuum line, pump up a vacuum with the handle, and then focus on fixing the problem.

[Project86]

Found the culprit guys!!! The cut vacuum source line!!! Now could I simply cut out this line, and run it to the corresponding spot on the selector switch? Also there is a black/orange Line that runs up towards the very top part of the firewall and seems to go under wiper cowl? Orange/black is for defroster but everything is hooked up so I don't think I'm going to mess with it

[motornut]

part 51,and 53 as in my 1988

[Project86]

Here's a pic

[Project86]

Now where this vacuum line goes to on the cluster of lines, there is an open spot with no hose attached when I removed everything. Would this be a problem?

[dpruim]

The one going to the passenger side colw controls fresh(outside) air into the system. Door should be closed only for Max a/c and off

[Project86]

Originally Posted by dpruim

The one going to the passenger side colw controls fresh(outside) air into the system. Door should be closed only for Max a/c and off

Allroght. So that's the orange vacuum line I see correct?

Sorry if I'm asking a lot of questions but I woul rather ask and get a better understanding

[motornut]

Originally Posted by Project86

Now where this vacuum line goes to on the cluster of lines, there is an open spot with no hose attached when I removed everything. Would this be a problem?

the 88 was like that, and a tee off over the top it seemed to go to a stop valve keeping the hot coolant from going through,IIRC

[Project86]

Thank for the pic motornut!!