fastdiablo

Was searching through some old threads about window defrosting. Are there best practices around how to keep the windshield from fogging up? I noticed when driving last night in cool weather that the windshield fogged up very quickly, but the only setting for the defroster was full blast with very hot air. The cabin got very hot immediately so I turned off the defroster only for the windshield to fog up again within minutes. I was not able to turn the fan speed down when the defroster was on, which seemed very odd, but I confirmed that this is normal operation based on the owners manual. Is anyone else experiencing this problem and have you found a solution? Why can't the fan speed be turned down when the defroster is on? It's very hard for me to fathom that the Germans would build something so impractical.

LexVan

Ignore the fan speed. Adjust the temp to be less warm. Why are windows fogging in the first place? Are you recirculating the cabin air or pulling in fresh?

CSK 911 C4S

Make sure your windshield is clean. I know when mine is less then optimal it gets a little foggy but goes away pretty quick once the HVAC has a chance to kick in. I usually run my HVAC on the AUTO setting.

porsche42

I get the same thing every morning. Sometimes I just crack the passengers side window and air circulation seems to work. Yeah I don't understand the defroster on full blast either it does work quickly is the only plus.

Porsche_nuts

Doesn't the defroster go on full blast on all cars in an attempt to resolve the fogging up issue as quickly as possible?

thomnellie

I have the same problem in winter and had it in a milder form with my previous Boxster as well. I believe the problem is that the interiors of these cars are very small, and the driver is very close to the windscreen, fogging the windows very easily. The heaters are very powerful, so that In below freezing temperatures there seemed be no option except to keep turning the defroster on and off. Irritating.

LexVan

Yes.

DNorby

I have the same problem. I just turn it on and off as needed. I bought some RainX antifogger but I have not tried it. It has a big warning not to put it on the outside, I would like to know what would happen if I did

TheEngineer

Have you tried selecting the far right button to direct the normal airflow to the defroster vents? You can then pick whatever temp and fan speed you want. If the car is getting too warm, dial down the temp and let the A/C kick on, it will serve as a de-humidifier and get some moisture out of the air. Also, make sure the re-circulate button is off.
I suspect the car fogs up quicker than 'other' cars because it is fairly small inside compared to a sedan or SUV; the moisture emitted by a person will drive up the internal humidity faster in a smaller air volume.

LexVan

Make sure HVAC is on auto sync too. Or else the right side if the car fights with the left.

fastdiablo

It does, but as in my outgoing Cayenne S, I could manually adjust the fan speed down to maintain a clear windshield, and I don't think it set the temp to full "High". I will continue to play with the settings. Last night I also noticed the extended vent setting (in AC setup menu) was off. Maybe that will help.

Yes auto sync was on. It was around 55 degrees out, sprinkling lightly, and I believe my interior was 68 degrees "auto" with AC compressor "On".

MKW

damp floor mats ( from tracked in rain / snow ) as well as inside glass " haze " build - up worsens fogging up tendencies also ...and as mentioned ...never have recirc on in foggy or rainy weather ......during a drive , all you can do is to heat up the glass as soon as possible and keep climate control on full " auto " so that the dehumidifying effect of the a/c is working in the background and always keep a clean rag within reach in worst case scenario of sudden blind out while at speed in traffic , since we all know it takes many , many seconds for the front " blaster " to clear the sudden fog up