Center vents are for air conditioning/colder air. Hot air comes out the sides, feet, and windshield while cold comes out the center. Turn the wheel to the coldest position and air will start coming out the center within a 30 seconds. Mine takes awhile to srespond sometimes.
Thanks
David

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2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

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