Hi friends!

I have a problem with my 2003 CTS, because when I turn on the A/C after a few minutes my windshield gets wet and I'm not use the defog function, this humidity occurs only outside, and I can get off just turning on my wippers, but its very irritating because the humidity block my visibility, specially when I rede at night, I supouse that my front defoger vent isn't completly closed, because I can feel when the cold air blows from the vent. Anybody know how can I close this vent (only when I don't use the defogger), or How can I solve y problem?

Thank You