I was a little surprised to see all the discussion about fogging windows in the manual. I'm no longer surprised. Why to the windows of the Prius fog so much quicker and often as my Highlander did? I realize the inside volume of the vehicle is much less but that wouldn't seem to account for the much increased fogging on a cold morning. Cold = 50 degrees in California
Is it on outside air? Mine on auto typically switches to outside when outside air is more than 5 degrees lower than SP to prevent fogging.
How long have you had your car and when is the last time you cleaned the inside of the windshield on your own? I ask because new cars can expel gas from the plastics on the dash and will leave a tiny clear residue on the glass, and the carwash doesnt always go through the trouble of reaching in there to clean it.
That's interesting. I haven't cleaned the inside of the windows yet, I'll give that a try. Purchased October 6.
Hopefully it will help to fog less and defog quicker. When I first got my new car I thought it had a crumby defroster, but now seems to be working better. I wouldn't use anything with rain-x in it, just a regular window cleaner.
One of my theories of more fogging (I noticed the same) is that the windshield and rear window are inclined at a very sharp angle due to aerodynamics of the Prius. They are more horizontal than vertical Today I was travelling with three persons on board (ambient temperature was abt 40F) and every few minutes I needed to use defogger. Also good idea is to crack-open one of the front side windows - just quarter of inch - it helped a lot. Not to mention to keep the glass surface top clean. See similar thread: Any advice on defogging windshield? | PriusChat
The steep windshield will also mean that anything like condensation and dirt film will interfere with vision more than it will on a more upright windshield. Likewise, more of what you see is the reflected top of the dashboard rather than what's outside, compared to a more upright windshield. This can contribute to eyestrain, and driving a car with a more upright windshield can seem to have dramatically better visibility.
Mine only demists the bottom half of the windscreen in the first few minutes when it's cold out (>10C), it takes another five to ten minutes to clear the top half. It seems as if the vents are not at the right angle to cover the whole screen.
I'm also thinking this could be due to the amount of open air you have inside the cabin. The Highlander, since it's an SUV, I'm going to assume has much more interior cargo than the Prius, which would result in a slower increase in the humidity and temperature change percentages you would see in the Prius. I noticed this the other day when I drove my parent's RAV4. It just felt less humid when driving, even with 4 people in the car. I'm no engineer or physicist so I can't make any claims to a sloped versus vertical windshield, but I wouldn't be surprised if this could play into it as well (since heat rises, and a sloped windshield would have the top of the glass closer to your head than a vertical windshield).
Rule 1 is always to try cleaning the window. Fog is just water vapor. And water vapor needs irregularities to condense upon (glass does have irregularities, but dirt makes it even worse). Clean the inside of your window. Use multiple rags, so you're not just smearing the dirt around. Then, make sure the heat is set to go toward the window. Eliminating the temperature difference between the window and the inside air helps eliminate the condensation. Warm air can hold more water than cold air. The air 1 inch from your window can be colder than the air in the car, leading to condensation. Finally, if you still have problems Rain-X makes a product for this: Rain-X® Anti-Fog - Rain-X They also make this product pre-applied to towels much like baby wipes.
And if none of the above works, get some cheap shaving cream and wipe it on and off the windshield. Mike
Turning-on windshield defogger enables A/C as well... As mentioned earlier - top-clean condition of the glass surface is substantial (I have my own set of wasted cotton t-shirts and old-fashioned baby cotton diapers - all washed on tight schedule). But the problem exists and this is the one and only one related to my Prius - as for mine three-month-Prius-experience. I drove various cars over 35 years in rather cold and wet climate and having a perfect view ahead is my obsession. Perhaps the reason is my profession which requires clear view ahead from the conn
Instead of keeping it in AUTO or turning on the defogger which blast AC at the windshield, switch the vent mode to "top defogger, lower air" will keep the windshield clear & cabin warm.
