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Help With 1981 A/C Issue

Old Feb 13, 2017 | 03:23 PM
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Default Help With 1981 A/C Issue

Hi All,

I recently purchased an 1981 Vette and have determined the A/C blows cold but only out of the lower floor vents. The console control appears to work OK, the vacuum lines are all attached to the controller, and I checked the A.I.M. in order to trace the vacuum lines and make sure they are all hooked up. As I followed the three lines through the firewall, the green strip and white strip lines look good and go to where they are supposed to go, but there is a third, thinner dimension vacuum line, black in color that is unhooked and I can't find it in the AIM nor can I figure where it should go.

My two questions are this:

1. Can anybody advise where this line might go? and,

2. Assuming the duct work is OK (it is), what would cause the upper panel vents not to blow air?

Any help is appreciated.
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Old Feb 13, 2017 | 03:43 PM
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in this diagram the blue and brown control the vent door

http://repairs.willcoxcorvette.com/w...-schematic.pdf
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Old Feb 13, 2017 | 04:24 PM
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Thanks, the diagram is very helpful.
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Old Feb 14, 2017 | 08:41 PM
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I have a 81 and a big issue with the upper vent does not meet up with the lower vent. this is seen when the center console is removed. Some have used duct tape and other items trying to close the open gap. This is the reason that side vent blow so strong.

Last edited by spedaleden; Feb 14, 2017 at 08:42 PM.
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Old Feb 18, 2017 | 12:17 AM
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Had the same issue with my 81. All the vacuum lines were hooked up as well. Turned out the control switch, which is plastic, was cracked, creating a vacuum leak not allowing the doors to open and close to bi-level and defroster. I just can't remember if it was the piece in the center console or behind the dash. I did have it removed to find it.
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