this is different than only defrost vent blowing

HVAC, heating, cooling, air handling. Anything air temp related.
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crash
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this is different than only defrost vent blowing

Post by crash »

I'm pretty sure vac lines are ok. I already fixed the blowing only on the defrost vent months ago.

Now, no matter where I have the vent setting, it comes out all over the place. defrost, dash vents and floor.... at the same time

the amount does change, for example, if on the defrost setting I feel it from the dash vent, then if I move the switch to the dash vent.. more comes out of them but it still has some coming out the defrost.
this is exactly the same regardless of which setting I'm not... it's liek it doesn't fully shut one off before moving to the next setting...

ideas? thanks
Rob
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current rides:
04 Mazda 6 V6 5spd

vans owned: Image
97 Astro AWD (selling by summer .. i think) SOLD
99 Astro LS Sept 08 ASV VOM
94 Astro LT
93 Astro LT
96 Astro LT AWD * parts van*
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kings-x59
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Re: this is different than only defrost vent blowing

Post by kings-x59 »

On the passenger side, up under the dash is an "air box" or plenum. There are dampers inside controlled by vacuum motors which you can watch operate, with the van running, after some minor disassembly. This is easy to get to from inside the van.
could be a bad vacuum hose up under the dash or a bad vacuum motor. Also, it could be something came loose inside and has blocked one of the dampers open.
As far as an issue with the dash switches themselves, someone else will chime in I'm sure.
'89 Astro, 4.3L, TBI. Minor intake and exhaust mods. Rebuilt 700R4 trans (by me). Corvette servo, 0.5" boost valve, police grade 1-2 accumulator spring (shifts fast and solid). B&M stacked plate trans cooler. Bilstein shocks. Belltech sway bars front and back. New head unit, speakers and subwoofer. Needs paint and a new headliner.

name's Steve
I can't remember all I've forgotten about that....
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crash
I plan to be buried in my van
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Re: this is different than only defrost vent blowing

Post by crash »

cool info kings. i'll have to check it out.

hmm.. probably totally unrelated to the hissing sound I hear on the drivers side after I accelerate hard and let off then I hear a hiss for a second or two... 8-[
Rob Image

current rides:
04 Mazda 6 V6 5spd

vans owned: Image
97 Astro AWD (selling by summer .. i think) SOLD
99 Astro LS Sept 08 ASV VOM
94 Astro LT
93 Astro LT
96 Astro LT AWD * parts van*
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kings-x59
I plan to be buried in my van
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Location: Cypress, Tx

Re: this is different than only defrost vent blowing

Post by kings-x59 »

If you had vacuum boost brakes, I'd say check the booster. If it were a booster leak though, you'd probably notice a change in the idle when you applied the brake. If you have hydro-boost brakes then my thoughts are moot.
'89 Astro, 4.3L, TBI. Minor intake and exhaust mods. Rebuilt 700R4 trans (by me). Corvette servo, 0.5" boost valve, police grade 1-2 accumulator spring (shifts fast and solid). B&M stacked plate trans cooler. Bilstein shocks. Belltech sway bars front and back. New head unit, speakers and subwoofer. Needs paint and a new headliner.

name's Steve
I can't remember all I've forgotten about that....
User avatar

Topic author
crash
I plan to be buried in my van
I plan to be buried in my van
Posts: 1289
Joined: Thu Sep 21, 2006 11:18 am
Location: Woodstock, Ontario

Re: this is different than only defrost vent blowing

Post by crash »

hmm.. ok .. reallllllllllll stupid question.. how do i know which brakes i have? ..
Rob Image

current rides:
04 Mazda 6 V6 5spd

vans owned: Image
97 Astro AWD (selling by summer .. i think) SOLD
99 Astro LS Sept 08 ASV VOM
94 Astro LT
93 Astro LT
96 Astro LT AWD * parts van*
User avatar

kings-x59
I plan to be buried in my van
I plan to be buried in my van
Posts: 1374
Joined: Thu Sep 21, 2006 7:50 pm
Location: Cypress, Tx

Re: this is different than only defrost vent blowing

Post by kings-x59 »

If it was a vacuum booster, you'd be able to see it no problem. Sits right between the master cylinder and the firewall.
Just noticed your avatar - funny! :muhaha:
'89 Astro, 4.3L, TBI. Minor intake and exhaust mods. Rebuilt 700R4 trans (by me). Corvette servo, 0.5" boost valve, police grade 1-2 accumulator spring (shifts fast and solid). B&M stacked plate trans cooler. Bilstein shocks. Belltech sway bars front and back. New head unit, speakers and subwoofer. Needs paint and a new headliner.

name's Steve
I can't remember all I've forgotten about that....
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