FI Flyer

The air conditioner tends to frost up the bottom of my windshield when I start driving the car after it has been parked in the sun. I know that the frost is on the exterior because the windshield wipers remove it but it reforms in less than a minute.

Turning off (or not using) the A/C is not an option. I have tried to play with the buttons that control the air flow (deselecting the up button while turning on the other two) but it did not resolve the problem. Changing the temperature setting to a higher number seems to work but that is obviously not an ideal solution when I am trying to cool myself and my car on a hot day.

Eventually the problem goes away but it takes quite a while and is annoying in the meantime.

What to do?

GSIRM3

Try adjusting the airflow so that the cool air comes only from the dash vents by depressing the button that indicates air coming from the dash vents. When in the Auto mode, some cool air blows out of the dash vents onto the windshield. That cools the windshield down to the dewpoint of the air which cause the condensation you see on the glass. The moisture is not frost, just condensation.

Palmbeacher

Ditto. I had the same issue (it's not only hot but also humid outside in FL) until I took it off AUTO and left it with just the dash vents open. I was reluctant to do it because in my Mercedes if it's not in AUTO the fan doesn't vary itself automatically to maintain temp. Not so in the Porsche, everything works the same as AUTO other than the vent selection.

chops

I have the same issue. This dreadful TX heat requires the A/C to be set to frosty.