algershick

iTrader: (1)

On the back of the TPI there are two small vacuum lines, one for the fuel pressure regulator and one for the HVAC. I have found numerous diagrams on the internet, and also photos of the line coming out of the TPI. My line is either cut or broken and I can't find out where exactly it enters the HVAC system. I've searched my engine bay, and tried to find pictures online to see exactly where it plugs in, but haven't found anything.

Does anybody have a picture of where exactly this line goes, or a description? This is on a 1986 Z28 with a LB9 if that makes a difference.

Thanks!

Austin

vetteoz

iTrader: (13)

Typically vac line runs to a one way valve by the dist before connecting to the HVAC hardline
( can't speak for F-Bodies but on Vettes the HVAC line is in the wiring harness on firewall)

TPI shown
In this case has side branch hose to the cruise control

Chevy86 IROC-Z

iTrader: (17)

My 86 IROC has the vac lines which goes into the cabin, is located on the main wiring harness to the left of the dizzy. It should be sticking out of the bunch of wires. I can provide you a picture tomorrow if youde, like, but you gotta remind me.

algershick

iTrader: (1)

I appreciate the quick replies, its a little late right now to go outside for a look but you've both helped me narrow down where I should be looking! I'd appreciate the pic tomorrow Chevy86, thanks again!

Chevy86 IROC-Z

iTrader: (17)

Yezzir. Like I said. Post something on this thread so that I can get an instant reminder on my iPhone like around 3:00 pm. Or If I remember, I'll take that picture for you.

algershick

iTrader: (1)

So no dice, I still couldn't find the line. Howzabout that picture, Chevy86.

Chevy86 IROC-Z

iTrader: (17)

Here it is. Behind the big wire loom is a smaller wire loom. There should be a tiny block tube sticking out of the wire loom.
IMG_0472.jpg?t=1325111797


You can see where my vacuum line begins to curve downward into the wire loom behind the connector...
IMG_0473.jpg?t=1325111793

Chevy86 IROC-Z

iTrader: (17)

updated.

algershick

iTrader: (1)

Thanks again, I'm going to head back out and take a look. Wish we had some of that sunshine up here in Washington right now.

Chevy86 IROC-Z

iTrader: (17)

Good luck man. If there is no tibe visible, then you may have to strip away some loom because the little tube may of had broken off and the rest is more than likey inside the loom.

algershick

iTrader: (1)

Chevy86 I think we're talking about 2 different lines, the line it looks like you're pointing to is indeed behind the plenum but not receiving vacuum FROM it. That line, at least on my car, runs across the firewall and tees in near the brake booster.

The line I'm actually looking for comes out the passenger side of the plenum near the rear. 1 line goes to the fuel pressure regulator, the other is supposed to go to the HVAC. Could you trace that one, and show me on your car where it routes to? Or anybody that wouldn't mind snapping a photo

Chevy86 IROC-Z

iTrader: (17)

Sure. I can take a picture tomorrow. You see, my IROC is different. Many others do have a t off. IIRC, it's for the cruise control. I don't have cruise control. So in a nut shell, my line goes from rear plenum, over to above the brake booster which has my vacuum ball/tank, then back to the passenger side and into the wiring harness.

algershick

iTrader: (1)

I finally took a picture of my loose vacuum line. I understand what you are saying about options effecting where this line could possibly go. My car came with factory cruise and A/C. Neither of those items are still on the car.

edit: I replaced my blower motor so now that works, but imagine that, the selector lever doesn't do anything. lol This little tiny line operates the entire HVAC control assembly?

Chevy86 IROC-Z

iTrader: (17)

The vacuum line controls a few thinks which are directly related to the HVAC controls just above the stereo. I'm not sure which but yes.

Chevy86 IROC-Z

iTrader: (17)

When I get time, I'll review my pdf GM Camaro Shop manual and let you know what I find.

algershick

iTrader: (1)

Thanks again!

algershick

iTrader: (1)

Well, both Vetteoc and Chevy86 were both right, I had just confused myself with the flow of the vacuum line.

I ended up getting a hold of a shop manual and from what it looked like in the diagrams, there is supposed to be a "vacuum tank" mounted between the brake booster and the wiper motor. The HVAC line should be plumbed into this tank. On my car at least this tank is not in this position.

I began tracing every vacuum line I could find starting from the drivers side of the firewall, tugged one that had a lot of slack- low and behold it wasn't attached to anything! I plumbed it into my loose manifold line and viola, the AC/heater head functions!

Sorry about the crappy pictures, its 10:30 and its a little dark outside. The first picture shows the connected end of the loose line that I discovered, which feeds the 1 way valve vetteoc mentioned.

The second is the end of that same line plumbed into the 90 degree elbow off of the short line from the manifold.