This morning, after driving for about 10 minutes at 60 mph along a fairly busy one-way highway in my '21 Tesla Model Y LR, the front windshield began to fog up a little. My wife wondered if it was inside or outside. Within 15-20 seconds the windshield had fogged so thoroughly that I absolutely could not see out of the car. I naturally slowed down immediately, but there was not much of a shoulder and I couldn't even see the shoulder out the front window (too dumb to roll down the window.) I pulled over as much as I dared, then tried, unsuccessfully, to activate emergency flashers; couldn't find them on the wonderful menu system (under pressure, forgot the switch on the roof panel.) Finally thought to turn A/C on and set max fan speed, whereupon the windshield began to clear after a minute or two and I was able to proceed. Very scary. I have no idea why the windshield decided to suddenly fog up after 10 minutes of driving. Outside temp was about 37 degrees.
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Windshield rapidly fogged to opaque
- Thread starter mikepo
- Start date
If you had to turn on AC and set the fan speed, it might be because you were not on AUTO in your climate settings? There's a dedicated front defog button that you can use, just like on other cars. I suggest you make it a shortcut on the bottom bar, just like the rear defrost.
Temperature change + humidity = condensation.
Probably your AUTO mode used a recirculation at that moment, and also there was a humid weather outside... because of no fresh air circulation, the humidity level increased in the cabin and fogged the windshield. AC helped because AC drys the air very fast.
Sometimes you may see the fog outside on the windshield. Usually happens at winter, when the windshield is very cold, but you drove in the area with warm air (in the parking garage for example), so this warm air condenses on the windshield in the form of fog. This also may happen during the summer, if you put the AC deflectors on the windshield and cool it down that way to the point when you see the fog from the outside on the surface of the windshield.
So, in the winter time, to avoid fogged windshield - put a hot air vent to the windshield.
In the summertime, usually during/after the rain, disable air recirculation and use AC.
Probably your AUTO mode used a recirculation at that moment, and also there was a humid weather outside... because of no fresh air circulation, the humidity level increased in the cabin and fogged the windshield. AC helped because AC drys the air very fast.
Sometimes you may see the fog outside on the windshield. Usually happens at winter, when the windshield is very cold, but you drove in the area with warm air (in the parking garage for example), so this warm air condenses on the windshield in the form of fog. This also may happen during the summer, if you put the AC deflectors on the windshield and cool it down that way to the point when you see the fog from the outside on the surface of the windshield.
So, in the winter time, to avoid fogged windshield - put a hot air vent to the windshield.
In the summertime, usually during/after the rain, disable air recirculation and use AC.
This happens because the passengers' respiration increases the humidity in the passenger cabin. Set the Climate Control to Auto and your preferred cabin temperature. Generally 68F to 72F will be comfortable. The Tesla Model Y climate system heat pump can simultaneously provide heat and automatically dehumidify the passenger cabin.
You can use the seat heaters and the steering wheel heater for enhanced comfort. (Tip: Set the seat heaters to the Auto setting. The Auto setting will usually get it right as far and providing enough but not too much heat.)
If needed you can manually activate the windshield defroster and defogger. Tap the climate control settings or the tap the temperature number displayed on the Tesla screen. Tap the windshield icon once and it will turn blue indicating that the defogger is activated. Tap the windshield icon a second time and it will turn red indicating maximum defrost has been activated.
You can use the seat heaters and the steering wheel heater for enhanced comfort. (Tip: Set the seat heaters to the Auto setting. The Auto setting will usually get it right as far and providing enough but not too much heat.)
If needed you can manually activate the windshield defroster and defogger. Tap the climate control settings or the tap the temperature number displayed on the Tesla screen. Tap the windshield icon once and it will turn blue indicating that the defogger is activated. Tap the windshield icon a second time and it will turn red indicating maximum defrost has been activated.
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This is absolutely, positively, 100% not a "tesla model Y" thing. Its already been explained by a couple people, but I have been in various cars where this happens and its always due to the passengers "respiration" (breath) in combination with the HVAC settings in the car.
I used to carpool with someone a long time ago that would be running the heat, fan on HIGH and wondering why in what passes for winter here in most of southern california (where it was still warmer than what OP mentions) the windshield would constantly fog up. They would be trying to wipe the windshield and drive at the same time, and I kept imploring them to "please turn on the AC... please turn on the AC, please turn on the AC or set it to auto at 70-72 degrees..." and they wouldnt listen.
I stopped riding with that person because of it, actually.
I used to carpool with someone a long time ago that would be running the heat, fan on HIGH and wondering why in what passes for winter here in most of southern california (where it was still warmer than what OP mentions) the windshield would constantly fog up. They would be trying to wipe the windshield and drive at the same time, and I kept imploring them to "please turn on the AC... please turn on the AC, please turn on the AC or set it to auto at 70-72 degrees..." and they wouldnt listen.
I stopped riding with that person because of it, actually.
gcardona
Member
Once the inside temperature reaches the dewpoint, fogging is pretty instantaneous. This means the humidity reached 100%
Not really; the passenger cabin is a relatively small space. With two passengers the windows will fog up twice as fast. The same thing will happen in an ICE vehicle driven with the climate control turned off. You could reduce the speed and degree that the windows fog by cracking open the window(s) to lower the humidity inside the vehicle. The only time I have had to activate the defogger setting has been entering the Tesla Model Y after it has been parked outside for a hour. As the outside temperature falls the windshield will cool and condense any moisture in the air both outside and inside the vehicle. The windshield wipers will clear the outside of the glass. The defogger will quickly clear the inside of the glass (you may have to also turn on the rear window defroster/defogger.)
I'm not sure if Tesla does the same thing, but I had a previous car where the auto climate automatically turns off the AC when the exterior temperature drops below 37 degrees. It was annoying, because I always had to turn it on manually.
The Y might do something similar, because there were a few times where after driving for a while the windows suddenly fog up. But that's why I also put a shortcut for defrosters on the launcher. (I always keep climate on auto)
The Y might do something similar, because there were a few times where after driving for a while the windows suddenly fog up. But that's why I also put a shortcut for defrosters on the launcher. (I always keep climate on auto)
The Tesla Model Y heat pump does not stop operating at 37F or even at temperatures below freezing.
CapsEngineer
Member
Happened in both my Edge and my MY in Mississippi when I’m driving early in the morning. Much easier to deal with in the Y. Press this button and tell it to defog the windows. Cleared them up quickly.
