Air Ony Discharges From Defroster Vents: All Lines Connected And Intact

garystocker · Jul 25, 2012

No hiss when selector is positioned between floor, def, vent, mix, etc.

I get a few pumps of the power brake via vacuum stored in canister when engine is off.

I followed the lines under the hood that run from pass firewall to passenger side vacuum tree, to across the firewall to the power brake booster vacuum tree.

Looks good under the dash. Connected and intact.

Now What?

blackstangt · Jul 26, 2012

If you have some vacuum tube lying around, try swapping it, you may have a crack somewhere hard to see. Try to open the vents manually (under the glove compartment), see if they stay. I wonder if testing using a vacuum cleaner would work or potentially do damage...

tca7291 · Jul 26, 2012

I was looking through my service manual earlier about this, and was thinking your defrost vacuum motor was stuck, but if that was the case you should still be able to get air on the floor vents as well depending on what you have it set to. I would assume a vacuum leak some where in the control, or maybe a clogged port on the control valve.

7991LXnSHO · Jul 26, 2012

A vac cleaner will not test lines. It has volume but not strength enough. A hand vacuum tester pump is made for that.

jrichker · Jul 27, 2012

Diagram courtesy of Tmoss & Stang&2birds

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Air Ony Discharges From Defroster Vents: All Lines Connected And Intact

garystocker

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tca7291

I can see your wieners.

7991LXnSHO

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