Ice buildup inside rear window

Do you ALWAYS have the front defroster on? That will keep the air dehumidified. I expect that the air's moisture condenses on the cold glass after you leave, and then freezes. The only solution is to fight the humidity before you park it. So even after your windshield is clear, leave the defroster running.

Those in cold climates can chime in as to whether recirc or outside air is better as far as minimizing humidity.

 

<div class='quotetop'>QUOTE(KTPhil @ Dec 4 2006, 10:58 PM) [snapback]357777[/snapback]</div>

I'm not in a cold climate now, but my past experience with them has been that cold outside air is usually the best for defogging.

 

<div class='quotetop'>QUOTE(PsyPrius @ Dec 4 2006, 09:39 PM) [snapback]357769[/snapback]</div>

Just reading this thread makes me cold....

 

Prius is the foggiest car I've ever owned. The defrost works OK, but he corners of the front windshield frequently stay slightly fogged. Don't have the hatch window freeze tho...

Why my MPG has gone from 48 to 34 is a much larger concern.

KenO



<div class='quotetop'>QUOTE(PsyPrius @ Dec 4 2006, 10:39 PM) [snapback]357769[/snapback]</div>

 

Haven't experienced the ice buildup problem here yet.

 

Cold outside air is drier than recirculated inside air. The flat angles of the glass make it especially easy for water to adhere and freeze once it condenses, so as the other poster suggested, try to stay ahead of the condensation by using more heat. I find the auto setting does a pretty good job in our cold climate, with me only occasionally having to key the defrost button.

Tom

 

you don't need to keep the defroster on to get the benefits of dehumidifying the air. Even though it's counter intuitive, keep the A/C button on. It doesn't necessarily cool the air, just "conditions" it - in this case, it removes the moisture from the air. Haven't you ever wondered why you'll be driving along, hit the defrost button, and the A/C light on a car comes on? Thats why.

With proper usage, you'll only need to use the defrost feature for a few minutes when you first get in the car, then running it normally with the A/C button on will keep the moisture, and thus the fog, away.

 

<div class='quotetop'>QUOTE(eagle33199 @ Dec 5 2006, 09:52 AM) [snapback]357900[/snapback]</div>

Interesting.

My experience is that if you keep outside air flowing, the inside will not steam up. If you put on recirc, the inside steams up - even with the A/C on.

Having driven an Acura Integra for 12 years before my Prius, and having driven in my wife's Corolla, IMHO, the Toyota A/C level is too low for effective dehumidifying of the air inside the car when recirc is on. My Integra had no problems with fogging when recirc was on. My wife's Corolla behaves similarly to my Prius in this respect.

So far, with my Prius, I need to keep A/C always on and intermittently run defrost in the Prius when ricirc is on. If I let in fresh air, the car is much less prone to fogging than with it off. However, when recirc is on the Prius is much less able to dehumidify the air with A/C on than my Integra was. It is about the only thing that I miss about my Integra.

 

Like the previous posters said, recirc is definitely better. I can't speak for the Midwest yet, but here in the desert, the outside air is always drier than the inside air, especially after people are in the car for a reasonable length of time breathing. My previous experience in the Deep South with other cars has been the same, recirc is better. I'll be experiencing the Midwest winter in our Prius soon enough, we're driving there for Christmas this year.

 

i had this problem with plain condensation on my Prius as well. i simply got one of those "dries the air" things for an RV. put it in the back, empty the water out every other day or so and that helps a lot. its either that or wipe it down with a towel every once in a while

 

<div class='quotetop'>QUOTE(Wiyosaya @ Dec 5 2006, 09:06 AM) [snapback]357903[/snapback]</div>

In humid conditions, such as the Midwest, Recirculation, is the worst setting. The air will almost always freeze inside a car that uses recir., in winter, due to increased humidity. Now the desert, I do not know. I also agree that the defrost setting is pretty weak. I am coming from a Saab 9-5, that absolutely BLASTED the frost/ice from the outside. Best system on any car I have ever owned.

Thank you for all I have learned regarding Prii on this site, I greatly appreciate it.

 

<div class='quotetop'>QUOTE(Wiyosaya @ Dec 5 2006, 10:06 AM) [snapback]357903[/snapback]</div>

Ah... another former Integra owner. That was a great car (1996), I miss that slick 5-speed shifting sometimes... :mellow:

I never had any condensation issues with my Integra either, and fresh air is definitely the way to go to clear windows. In fact, I always keep my cars in fresh air mode unless I need extra-fast heating/cooling.

One other point I would like to add, is if you have snow on the ground, do your best to knock your shoes/boots to track as little snow as possible into the car, as this is the biggest source of moisture in the car for areas that are afflicted with the white stuff.

 

My first winter with the car, in temps below -20 C and down to -42 C, without the winter front, I did have some icing and fogging problems even with the defrost on Max Heat and the rear defrost on. Barely any heat to speak of.

Now with the winter front, the coldest so far has been -27 C, and not a problem. Plenty of hot air to keep the windshield, side windows, and rear window clear.

If you're having fog/ice on the rear glass and the electric defrost isn't even clearing thin lines around the elements, you clearly have a problem with the rear defrost.