With AC, the fan runs on low all the time...even if you shut it off. It pulls in fresh air that way or so GM thought. I find putting the windows down much more effective.
Not sure why you're getting heat above the gauges. You shouldn't have any vents in the middle; only a block off plate that says "Corvette". The windshield defrost ducting runs up behind the gauges though.
Joel Adams
C3VR Lifetime Member #56
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"