help me find the vacuum lines

[chemist]

I've got the classic, only blows defrost problems too. Can one of you show me which vacuum lines to go after/where these vacuum lines are?

[webcat]

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[Matrixx]

Hi chemist

Is that plug-in on the inside (dash area) of the dog house or the outside (engine compartment)? I know the electrical plug-in hooks up to the dog house. If it's on the inside, then it looks like it might hook up to the Temperature Control Panel (in behind).

As for picture-2, that plug-in is normal to be like that (un-plugged).

As for picture-3, there appears to be a crack on the thin black vacuum line running in behind the alternator. That's the line you want to check very carefully for cracks and breaks from one end to the other. As for the blue plug-in sitting by itself in behind the A/C looks a bit unusual just sitting in that spot. Check in behind the A/C itself or the Vacuum Purge Solenoid that "should" be located where that thin black line ends at the Intake Manifold side of it.

PS: You might want to clean that Temp Sensor plug-in up a bit to remove that oil build up. The oil will eventually soak into the lines and will cause problems. Maybe just hit it with some brake cleaner or something along that line.

Thanks for the pictures chemist.

Hope this helps, let us know how things work out, thanks.

[stoneground1]

Hey chemist,
I really need to snag the last pic in your set. I don't have a pic of mine handy and it's dark here. I need it to post an issue about a crazy loud sound coming from that area. Hope you don't mind?

[MrFixIt]

Did you fix the vacuum problem yet? I had the exact same problem and found the small 1/16" vac line all dried up & cracked from heat. It runs from the left valve cover to the under hood on a fitting by the AC accumulator. Had to order from Chevy, as the GMC dealer is no longer in business, and could not find any similar size/type of tubing. GM part# is 15967970. It was $17 from the dealer but is available on line for under$10. Good Luck.

[maximus7001]

Heres what I did to fix that problem for good. I took an old ghetto blaster and pulled the antenna. Found the section of antenna that matched the o/d of the original hard vacuum line. Cut two pieces about 1 1/2" long from it with a dremel. Put the pieces in the fittings where each end of the hard line used to go. Used regular rubber vacuum hose to connect and voila, fixed forever.

[MrFixIt]

That sounds like a good solution. Someone suggested using a cloth covered rubber vac line used in VW's & Porsches which is likely available in bulk form. It might be possible to find rubber tubing with the same ID of the FITTING used at each end of the factory supplied tubing, which would slide over the barbs at each end of this line.

[teknowtron]

The posted images helped me find the break in the vacuum line very quickly, on my 2002 Astro 4.3 the break was at the connection on the driver’s side of the engine where it connects to the valve near middle of the valve cover (see picture borrowed from another posting). In the process of checking for bad connections I also pulled the hose off the vacuum ball located on the passenger side under the AC unit sticking out of the firewall, had to remove the air box plumbing that wraps around the radiator so I could get my arm down there and feel around for the connection. There is probably a better way of accessing it by taking the tire off and pulling the finder liner off but at 20 degrees in Michigan this week I was look to finish a.s.a.p. this hose was very spongy and needed replacement anyway.

[Phantom]

Here is some diagrams that should help.

[ALASKAN ADVENTURER]

The posted images helped me find the break in the vacuum line very quickly, on my 2002 Astro 4.3 the break was at the connection on the driver’s side of the engine where it connects to the valve near middle of the valve cover (see picture borrowed from another posting). In the process of checking for bad connections I also pulled the hose off the vacuum ball located on the passenger side under the AC unit sticking out of the firewall, had to remove the air box plumbing that wraps around the radiator so I could get my arm down there and feel around for the connection. There is probably a better way of accessing it by taking the tire off and pulling the finder liner off but at 20 degrees in Michigan this week I was look to finish a.s.a.p. this hose was very spongy and needed replacement anyway.

Thanks guys for the info, my 2000 AWD had the same vac line broken Replaced it with OLD School AIr Cooled VW fuel line it is raped with cloth, somebody on here said he thought it would work, it does thanks,