07 Rescue Green

You don't need to turn the A/C on, it comes on when defrost or defrost/floor is selected. Also, not to be an ass but it's the compressor not condenser. The condenser is mounted in front of the radiator.

Mark Doiron

Unless, of course, that's what's broken and manually turning it on works because it bypasses the broken electrical circuit.

GJeep

As you know, the AC is turned on because it reduces the humidity in the air. The drier air is heated (which further reduces its relative humidity), then flows over the windshield and evaporates condensation.
The hotter the air, the faster it works, so I turn the heating to high from the start, and it removes the condensation in seconds.

14Sport

That doesn't work for me. Not here in FL anyways. If I put it on heat it fogs worse. If I put it on cool, you can actually see it defog from the bottom up.

GJeep

Out of curiosity, I'd like to understand why it behaves differently in FL and over here.

Here, humidity reaches 75% , either in the pretty hot summer or in the winter.
In the summer, when the AC works, even with windows opened an inch or so, there's sometimes condensation, and adding the heating evaporates the condensation faster.
Today, much rain and 12 Celsius (~53ºF), I tried your way.
Evaporating was accelerated once I dialed to high heating.
Do you refer to lower temp' than 50ºF ?
Maybe the windshield is much colder to begin with, so warmer air that touches it shrinks much more, causing condensation?

14Sport

I have always heard that equalizing the temperature between outside and inside is what prevents condensation, and I've found that to be true, at least in my case. If it's warmer on the inside the condensation still forms, but on the outside. And vice-versa.

14Sport

I just googled it. I use the quick fix (equalizing temperature) option and you use the comfortable (evaporation) option.

How to Deal with Foggy Windows - The Allstate Blog

GJeep

I know the physics and what's the dew point, and that's exactly what I don't understand... why does it work the opposite way for me...

Quote from your link: "On a hot, humid day, the opposite happens, when the muggy air outside your car reaches the dew point against your windshield after it’s cooled by your AC system."

This happens both outside and inside my windshield.
On a hot, humid day, or rather evening, near the sea shore, I start driving, AC on, and get condensation inside the windshield...
Without turning the heating on, the AC alone won't cope with it.
I can only guess that the cold AC air creates yet more condensation or at least won't evaporate -- but that's cold air on a warm window...

There's condensation when taking something cold from the fridge out to warmer air, never when putting something in the fridge...

It's pretty silly to have to turn the heater on when its so hot outside, just to be able to drive... or having to turn the AC off.

jeepmojo

it helps if u stop breathing sometimes

14Sport

I hardly use heat, I hardly use AC. For me it's windows down immediately. That's the way I like it. If my inside window is foggy I blast some cool air on it and then shut it off again. If the outside is foggy I slap the wipers at it. With the windows down the temperature neutralizes quickly. I have used my defroster MAYBE 3 times since I bought my Jeep, well over a year ago, and each time less than 3 minutes. So I am by no means an expert. I choose the prevention route where you choose the cure. Both work.