On the 996 (99 & 01 for certain)series, and possibly the 986, the automatic mode of the climate control system will inadvertantly super-cool the interior surface of the windshield on a HOT day. If the day is also humid you may find yourself suddenly driving blindly down the road.

My experience was in the early evening after a very hot day in Alabama last July. As we drove through an area where it had just rained the entire windshield suddenly fogged over on the outside.

Porsche said that this is normal operation and advised me to be extremely careful about over-riding the automatic mode and only allowing cooling airflow to the dash and/or floor outlets to prevent this occurence.

In automatic mode there are no icons visible indicating airflow direction, but the windshield defrost outlets are in fact wide open allowing a great deal of cooling airflow to be directed to the interior windshield surface.

Summer's here, be careful out there !!!

Revision...

Unusually warm here today, 95+ discovered that the above problem does not occur until the interior temperature comes to within a few degrees of setpoint, until then there is virtually no cold airflow to the defrost ducts.

Once the cabin approaches setpoint it felt like as much as 50% of the cooling airflow was routed,automatically, out the defrost ducts. Don't know what the heat transfer charactoristics of the windshield glass might be, but I would guess that a great deal of the system's cooling capacity is wasted cooling the windshield and therefore the great beyond.