Hey, this already the third time. After a little rain, or some humidity around, my outside windshield gets foggy. I put on the ac defroster for the front, it clears the inside of the glass well. But there is like mist foggy spots building up in the outside windshield, more so in the lower to middle part of the glass. The wipers clear them, but I have to use it every like 10-15 seconds. I look at other cars with clear windshield. The AC works fine, I dont think I have a heater core problem, or other stuff etc, but then again I'm not the expert. What could this be?

 

Can somebody give me some advise?
BUMP BUMP

 

i'm assuming it gets foggy when its cold outside? Try turning the heat up on the defroster to get rid of it.

 

Try 70 degrees with the ac on

 

Well it was actually 65F last night. I had the ac window defroster set at 60F. I was like the only car driving with the wupers running, as the rain stop! The defroster took the mist inside the windshield, but the problem was on the outside, gets misty and all, then the wiperblade clears it, but as soon as it clears, it builds up again. I was reading about heat core, air draft, tempt on glass and overall tempt, cant figure exactly the deal? ?

 

Good tip. I've got the same issue with the vert on the realy muggy summer days. I may have to try a higher temp though since the top is down.

 

Our AC gets pretty cold and when u blow it on the windshield it'll create moist. Just try a higher degree with the AC on and see if that helps.

 

OK. Definately will try that. I hope i dont have leak on the heater core, as I was reading this causes this effect etc....... Its just weird how the mist pattern builds up right away as the wiper cleans it.

 

You know you're supposed to turn the heat up when using the defrost, right?

 

No I didnt, what effect does a front windshield defrost AC at 60F have on the windshield in a early summer day. 65F humid. vs a cold day. I use cold ac 60F defroster front in the summer and like 80F front defroster in the winter.

 

It's called "defroster" for a reason....it's there to DEfrost your windshield, lol.

 

If you make the windshield colder than the outside air, then obviously you will create condensation. By blowing 60 degree air on the windshield, you were making the windshield colder than the air outside. No different than a cold drink on a warm humid day, you get condensation. If it was 65 outside, then you should have been using the defrost at at least 65 to prevent condensation on the outside of the windshield.

And I don't know why these guys are saying you are supposed to use heat with the defroster. The A/C comes on when you use defrost, which takes the moisture out of the air. You can use your defrost on 90 or 60 and it will still remove moisture from the inside of your windows. Back in the old days that might not have been true, but all modern cars automatically turn on the A/C when you put it on defrost.

The "defroster" isn't just for defrosting ice. I've used my "defroster" many many times, but I've NEVER used it for ice or frost here in Houston. There's been many times that it's 90 degrees out and raining, and I have to use my defroster; and I'll be damned if I'm going to turn on the heat, no need.

 

Okay, time for a little science. There's a TSB for your problem - it's called the dew point. That's the temperature at which water vapor condenses. It's the reason why when you take a cold glass of sweet tea outside, the glass "sweats". That's condensation gathering on the outside of the glass, the liquid isn't coming out from the inside. Same deal here. Your windshield is cool (especially with you blowing 60 degree AC on it) and with the warming temp outside and some relatively high humidity (like right after a rain) - boom, condensation. Blow some hot air on the windshield and bring it up above relative humidity and it will dissapear.

If you don't have a garage, then this will happen most frequently in the morning. Your windshield is still cool from the cooler temperature overnight, and the outside air is warming more rapily than your windshield is. The people driving around with clear windshields probably just came from the safety of their garage, and that's why their windshields are laughing at you.

LOL - or read what mindonmatter wrote, he beat me to it.

 

AC has to remain on at all times. So if its like 75F outside, turn the tempt at least up to 75F on the ****. Stupid stupid question, if its raining and humid and its like 95F, hummmmm turn the defroster to at least 95F inside, that sure is hot. TSB, dew point good one. Does the heat turn on after a particular temperature?

 

Do you really think you will need to defrost anything when it is 75-95 degrees outside!