Dew on windows as I drive! Help! a/c settings?

Isn't that just normal in a hot, humid environment? Just don't set the a/c as cold I'm imagine.

Condensation forms on the outside of a cool object - think a cold bottle of wine brought straight out of the fridge. I guess it just shows your a/c is working well. I've heard from friends visiting Florida that this can occur. Perhaps some from Florida and similar could comment?

 

i've had this problem in moist foggy environments, especially in the as the night air sets in near the ocean. unfortunately, i haven't come up with a surefire solution. just keep fiddling with the dials and settings.

 

Central Floridian here. I have the same problem. When I parked in the garage I did not have the problem. If I run the defroster at the highest temp and fan setting it clears it then I turn it back on auto on a cooler temperature. This heats the windshield up to prevent condensation and when put on auto it comes out the vents as not to cool the windshield back down. I think the dew point earlier morning is the mid 70s so if you run the interior too cold the glass will condensate the dew once it reaches the dew point.

I only have a 2 mile commute at 7:30am so I only run the defrost for about 2-3 minutes. If you have a longer commute maybe turn the car/defroster on and let it run for 5 minutes before starting you commute.

 

i think it's the slope of the glass.

 

Try applying a hygroscopic film to the glass so that the condensate collects into droplets and rolls off. RainX is one commercial choice.

It would also help if your glass was not so cold. Try a somewhat higher interior temp setting with high ventilation. Try this:
AUTO AC
Set temp to 75 - 78
Set Vent to one of the high settings.

This way the system will control the humidity and temperature while letting you set the fan for comfort.

 

When you push the "AC Auto" button, it automatically sets the system to recirculate the air inside the car. What I have found is, turn the recirculate off so you have fresh air coming in. In my case, problem solved.

 

I see the 'AC AUTO' change the recirc as time passes. I'm pretty sure it sets a humidity point.

 

Pretty hard to control condensation on the "outside" of the glass. I think the Rain-X solution would be best for the side windows. Front and rear glass has wipers of course. Slightly warmer interior temperature would be tolerable with recirculate on to keep the humidity low inside the vehicle. This would keep the glass slightly warmer and less likely to condense water vapor on the outside. These condensation conditions happen only rarely here in Arizona, but they do happen. This time of year especially, like right after a heavy rain. You just have to fiddle with the controls to get some relief and hopefully not get into an accident. I have also found that at speeds above about 30 mph the side glass becomes self-clearing.

 

I have had the same problem in Texas and Fla. it helps to find a place on the AC control knob that does not put cold air onto the windshield.

 

That sounds like something to control condensation on the inside. OP is have an outside problem.

 

That sounds like something to control condensation on the inside. OP is have an outside problem.[/QUOTE]

Yep... And when I have condensation on the OUTSIDE of my windows due to having my ac on full blast set to "LO" and the recirculate icon is on, I switch off the recirculate and switch to defrost and no temp change and after a min or two, problem is solved. turn it back to vents with no recirculate and I don't have the problem.

I played around today, (92 F 54% humidity. If you have the ice cold recirculating ac blowing on a window, it will condensate as well. I kept my recirculate off and vents pointed away from the windows and never had a problem. Fwiw, dew point for today was 76F

 

Fuzzy, in the south, the dew point temperature can be so high that we can make water condense on the outside of glass if ac air impacts on the glass and lowers it's temp below the dew point. This was more of a problem with my old Benz with real Freon. But if we direct the chilled air at foot level or mid level, it allows the glass to remain warmer, hopefully above the dew point. On some cars if the HVAC door for defrost does not close fully by design or by fault, it can be necessary to plug the windshield outlet with a folded towel on humid days.