Front Windshield fogs in cold weather while not running | 2010 Prius IV

welcome to priuschat! in my experience, the windshield fogs up shortly after entering the car, especially if i'm singing. but i don't recall it ever fogging up just sitting there.

 

I noticed the windshield fogging up a lot recently. I have a gut feeling that dirt or anything thin film on the windows makes it fog up a lot easier - I cleaned the front inside glass last weekend and the fogging doesn't seem to be as bad but is still present

I'm not some science guru but fogging up of glass, wether it is your home windows or car windows is caused by moist air touching a cold pane of glass and condensing on it. Since you can't stop breathing, the best thing to do is dehumidify the car with the A/C function OR warm up the cabin with your hvac system which should bring up the temperature of the windows so that dewpoint cannot be reached as easily on the glass and cause fogging.

I think rain-x makes a treatment to prevent or minimize fogging of the windows. I have yet to try the treatment but its cheap - 6$ a bottle at most.

 

I'm not having any more problem with this car than my past cars, all of which have needed some active moisture control efforts in certain weather.

Besides human respiration, do you have other sources of moisture inside the car? Wet shoes / floor mats / clothing / sports gear / towels? If so, these should be removed and dried outside the car.

How are you using the climate control? Even with just human respiration, moisture can build up inside if the climate control is always set to recirculate, not adequately flushing the moisture released from occupant's lungs and skin. This may not be a problem most of the time, then suddenly cause inside fogging in just certain conditions.

 

I had some water in my driver side Husky liner leftover from snow/slush/rain mix from the last couple of days.
Overnight it dropped from 39F to 7F and the inside of my windshield was completely frozen up when I got in the PIP this morning. Took almost 30 min on full defrost with the ICE running to completely remove all the ice from it...

 

Yup, that's pretty much how mine looked this morning.
I'll have to be more attentive to mind the floor mats...

 

Isopropyl alcohol 70%, (aka rubbing alcohol,) does wonders on my son's glasses....

 

Bit of a passed thread.
But in my experience this 1st winter with my standard Prius I would say that I've discovered that the windows do have a tendency to rapidly fog up.

There are things I've always done with all my vehicles to attempt to minimize this reality. The most common being keeping the inside of the windshield as clean/dry as possible. And of course keeping moisture out of the vehicle as much as possible.

But I would say, The Prius just has a tendency to fog up rapidly. Then I would go further and say the defroster for front window....is passable...mediocre at best. If it's a winter evening or night and you are depending solely on the front window defroster to clear the fog off the window...you're in for a long wait.

I've taken to carrying something I picked up at the dollar tree in my glove compartment. Basically, I think it was made to clean dishes...but it's just a thin micro-fiber covered bit of sponge. It's thin, has grooves and can be folded. I just keep it in the glove compartment and if I notice the front window significantly fogged, I wipe it all down first. This really assists the defrost. The difference between waiting 3 minutes or more...or 1 minute or less.

Also this is just my experience. But while I like Rain-X products...I use it on the front window and I use Rain-X windshield wiper fluid, I've tried Fog-X and wasn't impressed.
Yeah, it would kind of keep the windows from fogging up...but for the life of me I couldn't really apply it without making it streak.
This was several years ago, perhaps they have improved the formula?

 

I sat in my best buddies' LEXUS IS350 on the weekend with 3 other ppl inside and the whole car fogged like crazy.

Perhaps newer cars have this problem. My older cars - 1989 civic and 1986 corolla never never had fogging this bad

 

One of my friends swears that putting Damp Rid in the car during the winter does wonders. The only time I have that problem is when I have the dogs in the car. I don't know what it is about their breath, but they do a great job fogging up the windows! Glad you figured out the cause and that it wasn't something more serious!

 

I'd call the Prius front defroster rather pathetic!
The problem is the defrost vents seem to restrict the airflow to the windshield. The fan seems to be working pretty hard- but there's just not a lot of volume of air hitting the windshield. Put your hand up there and check it yourself... there's hardly anything coming out.
If I put the defroster on full in my 2003 CRV it will literally blow a hat off the dashboard- the Prius defroster can hardly move a feather, even on full!

 

Well actually...so would I. I was trying to be generous in describing it as mediocre...

But I can't really remember a vehicle that I thought the defroster was worse.

But it can be compensated for...with just a minimal adjustment. I would say it is pathetic...but...hey no vehicle is perfect.

 

I agree, the front defroster blower part is a joke. Today I spent 15 minutes trying to defog the frigging glass......

 

A VW Bug with rusted out heater boxes may be slightly worse than the gen III Prius...

 

I actually park with the front of the car facing the sunrise now- it really helps. This morning when I was ready to leave for work at 8am the sun had melted the ice and the windshield was just wet.

 

One day last fall I had accidentally left the windows slightly cracked open over night. Of course it rained that night! The following morning I went to work (28 mile commute) and some of the windshield (near the top and near the rear view mirror) still had condensation on it after 40 min of full defroster action!

 

I've been doing this with nonhybrids for decades.

 

It helps to put the sun visors down. They block the respiration a little and help keep the heat from the defroster closer to the windshield. You also don't notice the frost as much since most of it is behind the sun visor. I did use the Fog X last fall. It does a good job keeping the moisture on the windshield from "looking" like fog, but once the moisture freezes...... well frost is frost.