astroventilation question
Thread Starter
Pro
Joined: Nov 2004
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From: North Alabama
astroventilation question
Did all 68-77 cars have this? or did the system change over the years...the chiltons manual seems to indicate that early models had the vents but not the vac operated doors.
Appreciate the help!
Appreciate the help!
Instructor
Joined: May 2006
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From: Albuquerque New Mexico
My 73 with factory installed AC had the vents blocked by two metal plates. I obtained an assembly off a wrecked 68, it mounted with no problem. Connected into the vacuum hose for the heater. Works great. Closed for the Heater or Defroster, open for Vent and AC. No more tornado effect when the windows are down.
Team Owner
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From: Southbound
Cruise-In II Veteran
Astro-Ventilation came about after the vent pane windows were discontinued following the '67 model year and meant only that outside air was supposed to be drawn through the cowl vents, out through the dash *****, to the back, and out of the car through the opening in the rear bulkhead. Cabin air was supposed to exhaust through the grilles on the rear deck.
The system probably never worked as well as the GM engineers hoped it would.
For AC cars, the two cowl vents on the driver's side were closed off with factory applied covers. AC system vacuum opened and closed the RH kick panel vent and the flapper door on the RH side of the cowl. These are supposed to be closed when the AC system is cooling and open for fresh air when the thumbwheel is set on Vent.
The system changed a little over the years. Some cars have vacuum operated rear bulkhead doors, others do not. Best way to determine what's correct for your car is to study the AIM.
Last edited by Easy Mike; Jan 18, 2007 at 02:01 PM.
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From: North Alabama
Thanks for all the feedback...this has become my new mystery to solve.
So the bottom line is, all non a/c astrovent cars would have vents in the back that open and close with either cable or vac. correct?
...So my 68 should have this system...
I have a feeling these may be hard parts to find.
So the bottom line is, all non a/c astrovent cars would have vents in the back that open and close with either cable or vac. correct?
...So my 68 should have this system...
I have a feeling these may be hard parts to find.
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Melting Slicks
Joined: Jul 2006
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From: Baltimore MD
Are you guys 100 % sure about this,i have a 69 350/350 ,4 speed with ac,and it has astro ventilation ,atleast it says it on the windows.And i think when i bought the car it was pretty much all original.
Le Mans Master
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From: Chattanooga TN
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A/C cars did not have rear vents. They had block-off plates instead.
EasyMike above gave a very nice explanation ....
Last edited by FrankVincent; Jan 18, 2007 at 05:27 PM.
Melting Slicks
Joined: Jul 2006
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From: Baltimore MD
My vents are operated by vaccum ,front and rear also.I will check date code,so all vettes had astro ventilation printed on the glass?
Last edited by Billysvette; Jan 18, 2007 at 05:24 PM.
Instructor
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From: Clearwater Florida
When the AC is set to NORM the cowl flapper door is open and the kick panel door is closed. This forces outside air to enter the fan, go across the AC evaporator where it is cooled, across or bypass the heater core (depending on the TEMP setting), and through the dash vents.
If the AC is set to MAX, the cowl flapper door is closed and the kick panel door is open. This forces air from inside the car to be recirculated across the evaporator as long as the TEMP control is set all the way to COLD. If the TEMP control is not all the way on COLD, the system defaults to the NORM settings.
If the AC is set to BILEVEL, the sytem functions like the NORM setting except outside air comes through the dash vents and through the floor vent(s)
On AC cars, the kick panel door is not a vent. No outside air is supposed to enter the cockpit through the kick panel door. Even when the system is set to VENT, air is supposed to enter the cockpit through the dash and floor vents and not through the kick panel door.
Race Director
Joined: Apr 1999
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From: NM
All NON-A/C cars from 68 through about 75 had the astrovent system. A/C cars did NOT have the system. All had the astrovent lettering on the side glass.
On astrovent cars the front floor vents were operated by cables mounted on the console. The rear vents were controled by vacumn and opened when the HVC control was set on Vent.
A/C cars did not have the front floor vents or the rear astro vents (rear was sealed off).
tom...
On astrovent cars the front floor vents were operated by cables mounted on the console. The rear vents were controled by vacumn and opened when the HVC control was set on Vent.
A/C cars did not have the front floor vents or the rear astro vents (rear was sealed off).
tom...
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From: Southbound
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Your non-AC '68 may not have opening vents in the bulkhead of the rear storage compartment. There should be grilles there with a filter element material behind them to exhaust cabin air, but they may not open and close. They do not open or close on my '68 convertible. The filter material is now being reproduced.
Up front, the non-AC cars have cable operated kick panel vents with the appropriate ***** on the console trim plate, left and right. In addition to these, outside air will also circulate through the vent ***** in the dash.
'68 AIM shows you the entire set up: AC and non-AC.
CAJOS: PM sent
Last edited by Easy Mike; Jan 19, 2007 at 10:08 AM.
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From: North Alabama
Your non-AC '68 may not have opening vents in the bulkhead of the rear storage compartment. There should be grilles there with a filter element material behind them to exhaust cabin air, but they may not open and close. They do not open or close on my '68 convertible. The filter material is now being reproduced.
Up front, the non-AC cars have cable operated kick panel vents with the appropriate ***** on the console trim plate, left and right. In addition to these, outside air will also circulate through the vent ***** in the dash.
'68 AIM shows you the entire set up: AC and non-AC.
CAJOS: PM sent
Up front, the non-AC cars have cable operated kick panel vents with the appropriate ***** on the console trim plate, left and right. In addition to these, outside air will also circulate through the vent ***** in the dash.
'68 AIM shows you the entire set up: AC and non-AC.
CAJOS: PM sent
I flipped through the AIM yesterday and you have confirmed what I thought I saw in it. This topic is interesting to follow...just when I saw it leaning one direction someone would chime in and send it another
Last edited by vettepilot68; Jan 19, 2007 at 01:00 PM.
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From: Southbound
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From: Redondo Beach, California
Your non-AC '68 may not have opening vents in the bulkhead of the rear storage compartment. There should be grilles there with a filter element material behind them to exhaust cabin air, but they may not open and close. They do not open or close on my '68 convertible. The filter material is now being reproduced.