Daves87IROC

Hello there, thanks in advance for any assistance you may offer. All I know is that my AC and heat work ok, but my cruise control does not. Is say just ok, because the AC isn't the coldest, and I have a leaky heater core . BUT they are at least still functioning for now.

This is for an '87 IROC Z28 5.7L 350.

I have read the stickies and a few seemingly related posts here to try and educate myself:
https://www.thirdgen.org/forums/cool...cuum-line.html
https://www.thirdgen.org/forums/cool...ve-vacuum.html

I am still lost, and admittedly not the best at mechanical stuff.

Here are my pics.





Upon inspecting my hoses, I noticed one is fed like it is going to go into the firewall, but instead it just curves around back towards to the front of the car and is just dangling unconnected. I am not sure if this was supposed to be hooked up somewhere under the dash/steering column, or if it is supposed to be here at the front of the vehicle.
Also, if you will see in my first picture, I have labeled a few things. On the larger vacuum thing (don't know what it's called) it seems there is something missing or broken off. Perhaps that is where this hose should be connected to. I don't know what the parts are called that these hoses are connected to either, so please bear with me. I have confirmed one of them goes to the big plastic bubble in the fender and seems to be connected securely.

One more thing: I hear a hissing sound from the condenser when the AC is running, should I be concerned? (Yes I realize how dumb that sounds)
Thanks for reading!

Daves87IROC

No love

Restrorob

iTrader: (7)

I'd give a hand Dave, But I'm in the same boat. All that stuff is disconnected on mine as well, I'm sure someone here can help us both !

paulo57509

The attached drawing might help.

What's not shown in the drawing is the large hose at the CC diaphragm. This large hose is the bleed off for the diaphragm and it goes to the brake pedal switch.

Notice on the drawing where Item 2 (Cap) is. The cap is blocking off one nipple of a check valve. I believe the cap is where the vacuum signal for the HVAC controls is hooked up to (a lot of GM vehicles use the same vacuum hook ups for the cruise and HVAC. My '92 Lumina is very similar to my IROC).

The check valve is important. Its job is the keep vacuum supplied to the HVAC system and the cruise control during periods of low vacuum operation (engine under load).

The spot you noted on the charcoal canister is for the canister purge solenoid.

Daves87IROC

Thanks very much for the reply! I'll see if this helps out and let you know.

Daves87IROC

Thanks again for your reply.
On the first attachment, hose #4 is definitely not connected anymore, but am confused as to where exactly it goes...I am guessing that it has to be connected somewhere down near the brake pedal, since that's where the cruise control switches are? If that is correct than this has become more daunting than I originally anticipated, because that is pretty far down into the engine bay.
As for the charcoal canister, I am at a loss, since I seem to missing that one top portion altogether.
At any rate, thanks for providing these, I have at least something to refer to down the road.

paulo57509

Looking at your photos, it appears that the hoses attached to the servo assembly are present and connected correctly. In the first attachment, Hose #4 attaches to the hose barb at the rear of the plenum, next to the vacuum source for the fuel pressure regulator. If Hose #4 is connected to the plenum, most likely the servo is leaking and not holding vacuum. Remove the small hose from the servo and attach a vacuum pump in its place and see if the servo will hold vacuum. Depending on how hacked your wiring is, it might also be an electrical issue.

Daves87IROC

Ah, but hose #4 as shown is not attached at all...I guess I need to try to wrap it back around and reconnect it! I really just needed you to confirm that for me.
I really appreciate it, I am going to try to reconnect it today.