When I bought this most excellent little car (with great gas mileage and reasonably cheap insurance rates), it was early spring in central Illinois. The weather was cold and rainy.
Now that it’s late spring/early summer in central Illinois, the weather is… cold and rainy.
The windows on this little car fog up in a matter of seconds just as soon as I sit down in it. Using the defrost usually doesn’t help; in fact, it seems to make matters worse. The defrost does, however, work just peachy if I turn on the air conditioner.
While I don’t particularly like running the A/C when it’s 55 degrees, it’s something I can live with. What concerns me is what’s going to happen when winter gets here. Proper use of a car’s climate control in the winter in central Illinois is a matter of life and death; as is being able to see through a clear windshield.
Long story short: will this situation change when winter gets here and it goes from cold and rainy to really cold and not-so-rainy? That is, is my foggy windshield’s reluctance to defrost a matter of the moisture in the atmosphere?
Also, is this typical of cheap Japanese cars? I’ve never noticed this problem before…
Try cleaning the inside of the windshield. If it’s dirty, it fogs up faster.
Also most manufacturers recommend you do use A/C when defogging windows. It’s faster and it helps the A/C to have it run once in awhile so gaskets don’t dry out.
Check to make sure that there isn’t a leak around your doors or windows, the extra moisture from a leak will cause a fogging problem. If there is a leak, you can wind up with bad problems in the winter with frost inside your windshield, I had that problem before. Don’t forget to check the sunroof and trunk, too.
If there isn’t a leak, you probably won’t have as much trouble in the winter, the cold outside air doesn’t hold as much humidity as warm air, so when you warm it up with the heater, you don’t get fogging. You do have to wait for the heater to get going, though.
The A/C works well in the Spring - Fall because the A/C will drive out moisture when it chills the air and deliver drier air to the passenger compartment. The dry air will absorb the water from your windshield and clear up the fog.
It has to do with moisture condensing on a cold surface. When it’s raingin and you are wet, you are introducing warm moist air (including your breath) in a small volume (car) and it condenses on the cold windsreen.
What the defogger must do is cause the moisture to evaporate. One way this can be done by blasting warm air over the windscreen (warm air can hold more moisture than cold). This also warms the windscreen so it’s tougher for moisture to condense on it.
The other way is the air-conditioner trick. Since the a/c has a condenser as part of its circuit, the air blown out is dry. The moisture on the windscreen will evaporate quickly into the dry air.
This can also be a symptom of a leaking heater core. Do you get little whiffs of antifreeze every so often. I had a car that would fog up inside in the winter and would send just a hint of antifreeze in when the thermostat kicked in.
This is probably obvious, but also make sure that your air source is set on “external” and not on “recirculate.”
If you have a humid interior, setting the defogger on “recirculate” (but without the AC on) will often make the fog problem worse before it makes it better.
So you get in, sit down & the windows fog up? Did you try this without turning it on first? Cause that’s the first thing I would try & of course, a bottle of FogX would be next. After that come more serious things.
Is it possible for you to run the air conditioning as you’ve been doing, but with the temp control over on the “hot” side? I always thought that was the standard way to clear a windshield. “Air Conditioning” doens’t mean the same thing as “cold,” because as others here have pointed out, the AC dries the air out too. When my windshield ('95 Mazda Protege, 175,000 miles) fogs, I just direct the air to the windshield, push the button that turns on the AC, and slide the temperature lever to wherever it’s comfortable, even if it’s way over on the hot end of the selection. I use it frequently in the winter when it’s cold & rainy.
If your car’s AC and heat are controlled by a thermostat (where you set it at a desired temp rather than select from a continuum of hot air…cold air) you may have to “manually override” that feature.
This definitely could be the answer. Most people don’t even notice if they are using “external” or “recirculate”. It can get switched for numerous reasons. It is the first thing I check when the windows get fogged up.
Check out this thread and scroll down to Philster’s post.
You’ll find out that pushing the AC button is the best way to defog, even in the winter. You’ll also learn why you didn’t have to do this in the cars you had before.
