Cavalier Starting in the 1980s. the Cavalier made a name for itself by offering an affordable 2 and 4 door compact.
Platform: J-body

Errant vacuum hose

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Old Aug 27, 2022 | 7:22 PM
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Default Errant vacuum hose

Ok so I just got the 1991 cav. There is a vacuum leak which you can tell when you press the brake.

Coming from what I think is the heater core housing is a vacuum line with a fitting about the size of a half dollar dangling. It goes someplace but I can’t figure where.

If you know please let me know. It’s about a foot long or so.
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Old Aug 27, 2022 | 8:32 PM
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Originally Posted by Crajnai
Ok so I just got the 1991 cav. There is a vacuum leak which you can tell when you press the brake.

Coming from what I think is the heater core housing is a vacuum line with a fitting about the size of a half dollar dangling. It goes someplace but I can’t figure where.

If you know please let me know. It’s about a foot long or so.
Is your HVAC system working OK? Could you upload pics of the hose?
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Old Aug 27, 2022 | 8:33 PM
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AC blows hot. Haven’t checked heat yet. I’ll get pix tomorrow.
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Old Aug 28, 2022 | 3:27 AM
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Originally Posted by Crajnai
AC blows hot. Haven’t checked heat yet. I’ll get pix tomorrow.
You are in the right place, Crajnai.

I studied A/C systems back years ago when I intended to become a mechanic, or an automotive technician, as they are called now, and have repaired A/C on many systems and converted the old R-12 system to operate on the new R-134A refrigerant..

Most newer vehicles don't use vacuum to control things like they used to, and use electronics instead, but I am an OG but still an expert on modern A/C systems. If you can supply enough information that I'll need, I can likely help you to repair this issue.
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Old Aug 29, 2022 | 8:21 AM
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Thanx Henry. Here is a pic of the dangling hose in my hand. Where does this go. Is there something missing from it?


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Old Sep 3, 2022 | 4:20 AM
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Originally Posted by Crajnai
Thanx Henry. Here is a pic of the dangling hose in my hand. Where does this go. Is there something missing from it?

I looked all over and could find that part. It has to be reachable by it’s hose length. It doesn't look like any HVAC component I've ever seen.
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Old Sep 3, 2022 | 8:55 AM
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Do you think it’s vacuum hose? I tried again and can’t figure it. Took the air cleaner off. It doesn’t belong anyplace obvious.

Logically if it is vacuum, it need to go someplace that has vacuum to provide, which to me would mean intake someplace. When the engine runs, it has no vacuum on it.

Im stumped. Is there a vacuum line schematic someplace that may help? Is there a free Service manual I can borrow from someplace here?
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Old Sep 4, 2022 | 12:28 AM
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Originally Posted by Crajnai
Do you think it’s vacuum hose? I tried again and can’t figure it. Took the air cleaner off. It doesn’t belong anyplace obvious.

Logically if it is vacuum, it need to go someplace that has vacuum to provide, which to me would mean intake someplace. When the engine runs, it has no vacuum on it.

Im stumped. Is there a vacuum line schematic someplace that may help? Is there a free Service manual I can borrow from someplace here?
I'll see if I can find it, but according to what I see it has to hook up to the engine vacuum someplace,
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Old Sep 4, 2022 | 12:32 AM
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Originally Posted by Crajnai
Do you think it’s vacuum hose? I tried again and can’t figure it. Took the air cleaner off. It doesn’t belong anyplace obvious.

Logically if it is vacuum, it need to go someplace that has vacuum to provide, which to me would mean intake someplace. When the engine runs, it has no vacuum on it.

Im stumped. Is there a vacuum line schematic someplace that may help? Is there a free Service manual I can borrow from someplace here?
I'll see if I can find it, but according to what I see it has to hook up to the engine vacuum someplace,
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Old Sep 4, 2022 | 1:00 AM
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Originally Posted by Crajnai
Do you think it’s vacuum hose? I tried again and can’t figure it. Took the air cleaner off. It doesn’t belong anyplace obvious.

Logically if it is vacuum, it need to go someplace that has vacuum to provide, which to me would mean intake someplace. When the engine runs, it has no vacuum on it.

Im stumped. Is there a vacuum line schematic someplace that may help? Is there a free Service manual I can borrow from someplace here?
I'll see if I can find it, but according to what I see it has to hook up to the engine vacuum someplace,

I found this vacuum motor/pump. It looks like it fits the picture you uploaded but would be used to supply vacuum to this device, which I can't nail down, I'd check your HVAC box for some sort of place this might go. I can't find a diagram for it either, does your A/C compressor ever engage at all?

https://www.partsgeek.com/parts/vacuum_pump.html

Last edited by oilcanhenry; Sep 4, 2022 at 1:02 AM.
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