Humidity on front windows, can hardly see!

Clean your window too. Particles ("condensation nuclei) help condensation form
 
Because all the previous cars I've owned defrosted with A/C on and HVAC set to defrost.
Besides it's hot and humid in the morning.

Blowing super cold air on windshield with high humidity outside will cause condensation on outside. You must make air warmer or dont blow cold air on the windows.

If condensation is on inside, you must not be on recirc and you are pulling in super humid air.

Either way air is making glass to cold, so make air less cold.
 
Driving usually helps too because the friction of the air moving over the windshield rapidly warms it up to the ambient air temp. But in the meantime, warm up the engine and direct some heat at the glass.

Um, what? If you were driving faster than the speed of sound this may be true, frictional heating doesn't occur at low speeds. It's not friction heating the glass but the moving air absorbing the moisture and then the glass warming to ambient temps.
 
Last edited:
Um, what? If you were driving faster than the speed of sound this may be true, frictional heating doesn't occur at low speeds. It's not friction heating the glass but the moving air absorbing the moisture and then the glass warming to ambient temps.

That's a more extreme type of friction but nonetheless air molecules bouncing off the windshield exchanging heat with it is a friction. Thus moving air brings a cold windshield up to ambient faster. Same way air cooling works except in the other direction.
 
Only time I've had condensation problems on the inside screen was when I had inadvertently left the air intake on recirculation.
 
Heat and AC to dehumidify actually.

This... we se the A/C year around as it takes the moisture out and keeps the windows clear, in the winter just turn the temperature up and you will get hot and dry too...
 
It's a catch 22 situation. Wev'e had lots of morning fog here the past few weeks so I have this problem as well. Putting the defroster on cycles the a/c, it's just what it does to dry the inside air, which in turn makes the windshield cold and condensation forms on the outside. So, you turn the heat up to dry the outside. Except when it's a warm, muggy morning it gets pretty unbearably warm in the cabin.
 
I live in Heat and Humidity Central (South Florida) and at 6:45 in the mornings and most days, no matter the season, theres dew on the exterior glass. I have to set the temp to high and turn on the defrosters to keep the windshield from fogging up again. I only have run it for about 10 minutes until the windshield is warm enough.
 
I feel your pain - MD this year has been horrible. As gross as it sounds, when it's 85 degrees and 100% humidity, I run the defroster for a bit. And yes, on a 75-ish degree setting. It gets rid of the fog on the windows and dries out the cabin a bit. I turn it off after about 5 minutes (it's all I can stand) (rant)
 
If you run the climate control in auto without overriding the A/C, you should rarely see any mist on the windows. If you do, it would be because maybe you collected a couple of passengers on a rainy day who are wearing rain soaked clothes.

The only reasons that would not be the case is that the cabin filter is blocked, the recirc button is pressed, the A/C needs re-gassing.
 
You could also have a problem with fog on the inside if your drain from the AC under the car was plugged...
 
Back