Hey,
I use my 09 911 year round. Just wondering if anyone ever gets frost on the inside of the windshield? I actually have to use a card to scrape it.

It's happening quite frequently. Only the front glass not the side windows or rear.... Any ideas?

 

Maybe your window seal is letting cold air seap in causing frost

 

Anytime I've had ice on the inside of the windshield it was heater coolant related...

 

It could also be the water/moisture in your carpets from your shoes.

If you can leave the sunroof tilted or window cracked open on a dry night, it might help reduce the build up.

 

Moist air blowing on inside of freezing windshield. Are you running the AC with the heater/defrost? Thats the default setting. I don't switch AC off until at full running temp. Also try vents open or closed to see which works best. My M3 used to do that trick but only on those damp cold days that are unusual in the winter. If the moisture is coming from interior as NV suggests I think open will work better. From outside the opposite.

 

If you are driving in cold weather, make sure your recirculating air setting is off. Recirculating cabin air in cold weather can cause fogging and frost on the interior of the windshield.

 

Potentially the heater core? First tell tale sign. Check your passenger side carpets under the dash to see if they are wet/moist.

 

Hey MB007, I'm also in Toronto and drive year round. I haven't experienced what you have however the same weather experience, my settings are:

23.5C
ECO light on
Air directed to windshield, floor and front nets (all 3 arrows on)
Recirculation off
Fan at 30% strength

I rarely change this and have no issues. Oh ya, seat heater ON...

Good luck

 

Also have an '09 (C4S coupe) and daily drive in central MN winters - no frost (inside ;-))

 

This happened to me because of a heater core leak. I had to replace the core. I took almost 6 mo for smell to go away. Do you have a sweet coolant smell?

 

Hey, so it hasn't been overly cold... I've tried to make an effort to make sure I've switched the AC off now when I turn off the car and I haven't had the frost on the inside... Just glad its not a seal or the heater core... Knock on wood

 

Great advice. I get that in my truck and need to stop recirculation.

 

Glad to help. You shouldn't need to turn off the AC, just make sure the recirculation button isn't on.

 

Haven't had the problem in any of my 5 Porsches since my 356C! Something obviously wrong.

 

Whats the snow flake icon on the led display on the thermost stat? I cant seem to get rid of it.