Window Misting - Safety Hazard

[Asciidv]

i have 2 month old S 90D. It has a characteristic which I hope is just unique to my car. It is a problem which occurs on damp days when the windows start to mist up. After the heater and front screen heater is turned on, the front windscreen mists up totally in a couple of seconds preventing visibility. After about 20 seconds when the heat comes through the windscreen clears. The first time this happened I nearly crashed.

Has anyone else experienced this?

I think you can tell that this is a car designed in a place where it rarely rains. Here in Northumerland the rear window is rarely useful as it doesn't have a wiper, the rear view camera is always dirty and the wing mirrors don't seem to clear of rain easily.

 

[pbceng]

Hi there, you have probably figured this out by now but I've only just noticed your post.

This is a typical problem with aircon systems where when you stop the car all the moisture extracted out of the air gets dumped as the matrix heats up. When you then start the car on a damp/cold day the moisture hasn't evaporated away and the initial blast of air is at 100% or near humidity.

There are two approaches you can take;

1) turn off aircon in the cold months when you don't really need it. The only thing to be aware of is that you need to run the system for at least 10 minutes every week to make sure the seals get lubricated and also clearing windows in heavy rain or damp conditions may take a bit longer - a quick 10 min blast can do the trick here though.

2) as you approach your destination manually turn the a/c to off, then put fan speed to high for about 30 seconds. This clears out the moisture. When you start up you need to remember to turn the a/c back to on or auto assuming you need it and likewise set the fan speed.

I use the first method and it works for me!

 

[thegruf]

better still just preheat/cool the car from the app 10 mins before you drive.
Fantastic feature, never had to scrape/demist the windscreen since I had the car.

The camera just gets a finger wiped over the lens whenever I put it onto charge, mostly this keeps it clear and is no big deal once it is part of the routine, had to do it on previous cars as well, not just a Tesla issue.