Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Side windows fogging (just in cold?)

This site may earn commission on affiliate links.

wayner

Active Member
Oct 29, 2014
4,299
1,791
Toronto
I have had my car for only 12 hours - and in that time it has been very cold here in Toronto. Last night when driving home with my wife both of the side windows fogged up - I thought this may have been due to excessive moisture in the car as we were sitting in it for our training. Today while driving to work my passenger side window fogged up. I tried adjusting the heating vent to blow on the window but this didn't really help. Climate was set on Auto. Anyone have any advice on how to minimize window fogging?
 
Wayner do you have the full front dash vents on your car? In the early cars these weren't present and were retrofitted to all the northern cars. Not sure if every car is built that way now.

On reflection I think every car has them now. The other thing is make sure your car isn't on recirculate, take it off auto and make sure you are getting outside air to the vents.
 
I have found that when it gets really cold, having the HVAC set to pure Auto is likely to lead to windows fogging up. Auto typically routes the airflow to the floor, which is not helpful on the windows. I go to manual settings: A/C off (although turn on for extra moisture removal especially if recirculate is on), Fresh air (not recirculate), windshield and front vents selected, and Fan set to auto or 9.

I have found the recirculate/fresh air settings make a huge difference in the winter. Recirculate uses a bit less power to heat the cabin but leads to windows fogging quickly. Setting the car to fresh air usually clears up the windows quickly. When it gets really cold, I may toggle back and forth between the two to keep the side windows from fogging up.
 
Push the defog button (blue setting not red) and leave it on. If it still fogs (this may happen occasionally in extreme cold) then increase the fan speed manually.

When I first got the car this was a BIG problem, but some changes to the HVAC controls and the addition of physical vents in the dashboard has pretty much resolved it.
 
Just a remark, it was stated to always have the defog active.
Pushing it once the defog starts, pushing it a second time brings the defog to the selected fan speed.
I only found out about this a week ago, my car was delivered to me March 14 and think it came with a software upgrade, all new owners are told about new functions but the earlier owners alike me probably do not read the release notes that well.
I also found pushing the roof of the key twice unlocks the charge cable of the charge port, handy when the cable was to be taken out, the new upgrade we will get soon (some new cars have that upgrade already) will allow opening the charge port by pushing the rear window this to get the charge cable attached.

Rests me to say, enjoy your car, I love mine!
 
Hi guys - my wife hit the defrost (red, not blue) yesterday when I was driving to our accountant's office (30km trip each way) and it was very cold outside, side windows were very foggy. Within 4 minutes they were clear. Next time I'll try Doug's suggestion of defog to see if it makes much difference.
 
Hi guys - my wife hit the defrost (red, not blue) yesterday when I was driving to our accountant's office (30km trip each way) and it was very cold outside, side windows were very foggy. Within 4 minutes they were clear. Next time I'll try Doug's suggestion of defog to see if it makes much difference.

The issue I have with defog (blue) position, which works great to avoid or eliminate fog, is that you get nothing to the foots and over time you'd get cold foots.

That's why, I keep manual setting for only windshield + foots and although the fan (on auto) works a bit more you get warm foots and clear windows.

IMG_5191.JPG
 
I have been fine using Auto setting. You could check to make sure your dash vents closest to the doors are not closed off and are angled towards the side windows. They are tricky to angle towards the windows without shutting them off (assuming the design of them has not changed since my car). On my car, even though the air says its coming out at the feet, a substantial amount of air still comes out the defrost vents which keeps the windows clear when on Auto setting.
 
Depending on the conditions, the Auto setting may set the fan too low to keep the side windows clear. If that is the case, manually increase the fan speed. I find the auto settings are sufficient 95% of the time. (And even then I usually just up the temperature half a degree instead of adjusting the fan, because it's easier.)

All that said, the HVAC system work TONS better than it did two years ago. They've made leaps and bounds improvements in the firmware updates.
 
As part of replacing a faulty 12V, I asked the SC to look at the HVAC: I've had the system blowing out cool air when it was -17°C outside and interior was set for 23°C. They updated the car to 6.0 / 2.0.xx and it seems to have made a big difference.