Can't change from defrost to vent or heater. Help!
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Joined: Oct 2002
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From: Ontario
Car: 1991 Camaro RS
Engine: 406
Transmission: T-56
Axle/Gears: 3.42s
Can't change from defrost to vent or heater. Help!
So what did I unhook that controls where the air comes out inside my car. No matter what setting I put it at it always come out the top fo the dash(Defrost).
So when I change a setting on the dash what controls where the air comes out? vacuum line? is it electrical? or just a simple mechancal hookup?
So when I change a setting on the dash what controls where the air comes out? vacuum line? is it electrical? or just a simple mechancal hookup?
Thread Starter
Senior Member
Joined: Oct 2002
Posts: 859
Likes: 0
From: Ontario
Car: 1991 Camaro RS
Engine: 406
Transmission: T-56
Axle/Gears: 3.42s
is it a vacuum line that controls it tho? I've had the vacuum line that runs the heater core valve d/c all summer but have always been able to change air directions still since till now. Not sure if I hit something installing the new heater core if maybe even taking out all the AIR emissions did it(elec stuff). Thats all ive done since it stopped working.
Joined: Mar 2000
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
If you're talking about the vacuum-operated valve under the hood connected to the heater hose, that's not what he's talking about.
The heater control has a vacuum router on it. It gets vacuum from the engine, via a small plastic line on the back of the TB/intake manifold, which passes through the firewall. The switch routes vacuum to various servos, which in turn route the air flow to the proper spots. If that line, or the switch on the control, has been disturbed, your controls won't work properly. The default (no vacuum applied to any servos) is defroster.
The heater control has a vacuum router on it. It gets vacuum from the engine, via a small plastic line on the back of the TB/intake manifold, which passes through the firewall. The switch routes vacuum to various servos, which in turn route the air flow to the proper spots. If that line, or the switch on the control, has been disturbed, your controls won't work properly. The default (no vacuum applied to any servos) is defroster.
Thread Starter
Senior Member
Joined: Oct 2002
Posts: 859
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From: Ontario
Car: 1991 Camaro RS
Engine: 406
Transmission: T-56
Axle/Gears: 3.42s
thx for the info five7kid. Was looking all around the dash yesterday and noticed it's a setup as you speak of. Still have yet to find the leak if that's indeed the problem.
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From: AZ
Car: 88 Camaro POJ
Engine: 350
Re: Can't change from defrost to vent or heater. Help!
same proplem im having where is the vac supposed to come from? got this car not too long ago guy before me swapped motor and trans hard to make heads or tails did sloppy work
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From: Colorado
Car: 83 Camaro Z28 (CFI)
Engine: 305 V8 (CFI)
Transmission: 700R4
Axle/Gears: 3.73
Re: Can't change from defrost to vent or heater. Help!
You may need to install a check valve. Like on me JeeP for example, when running the heater or ac the air wold keep switching between the dash vents and fronts vents (very annoying). I installed a $6 check valve and all is good now. Perhaps it will work in this situation also. See post #4 in this thread here for the fix:
http://www.jeepsunlimited.com/forums...d.php?t=553785
I know its for jeep but it will give you a general idea for a fix
http://www.jeepsunlimited.com/forums...d.php?t=553785
I know its for jeep but it will give you a general idea for a fix
Last edited by Billyjoebob007; Jul 10, 2013 at 01:25 AM.
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