A/C blowing out of defrost vents - Condensation/fogging

I live in Florida. Everytime I turn on the A/C front vents only. The windshield will condense and fog up on the outside of the glass, center lower portion. I noticed that the cold A/C blows out of the defrost vents against the windshield even when the defroster is set to off.

Is this normal or anyone have a solution?

Thanks

 

Is the Recirculation button turned on?

 

Yes it is

 

Nature of the beast; cold air on one side, hot air on the other. The only thing you can do, if you must have it on the defrost setting, is to turn up the temp. until it doesn't cause condensation.

 

So there's no way to have ac on with defrost vents off? I don't understand why there would be cold ac blowing on my windshield when select front vents only.

 

normal

 

But why? Doesn't make sense.

 

It's not a solid seal when the motor actuated door blocks the defrost vent. Cold air still flows by a little. My 2nd gen started doing it after about 60k on the odometer.

 

Some years ago, many/all manufacturers started running the ac with the defroster to reduce the amount of moisture in the defroster's blown air. Sadly, the even colder (but drier) incoming air is fighting with the heater. On some/most vehicles it works. On others (i.e.: Jeeps) not so well.

 

Its weird bc my other cars I never had this problem. So the cold air coming out defrost vents is normal. Seems like it should just be sealed off unless you actually use the defroster.

 

Put a cold coke can outside. What happens ?
Outside moisture condenses on cold can. Dew point.
Anytime you lower the outside temperature on the glass lower than the dew point it will condense.

You are in the cold can (truck), moisture is on your windshield (outside of can).

Only thing that would eliminate this is having the air blow out in a more diffused pattern as not to concentrate on one section of the windshield aggressively and become colder than rest of area.

 

I understand the coke bottle. I just don't understand why the cold air would be blowing at the windshield. I wish there was option to turn it off or better sealed.

 

Always an option, fix the problem yourself or have someone else do it. Had a Jetta that did that, ripped the dash apart. Actuator wasn't pushing it all the way in, wore out from age I guess. Cut the link, enlisted a coat hanger to add extra length and got it to work. Always options. Since yours is a 2018 i'd option it back to the place you got it and have them fix it

 

Really depends how much air is blowing out your defrost vents. Very well could be a faulty actuator or blend door. Your under warranty so have the dealer check it out

 

I run AC a lot in very humid conditions, and I have never noticed this on my 18. Yes condensation is normal, but blowing cold air through the defrost vents is not in my experience. Might be worth a discussion with your dealer.

 

It's an option the dealer can change if you have auto a/c. See attached.

 

I noticed the same thing in my 18 the day after I bought it. I've never owned a vehicle that fogged windows so easily so it caught me off guard. Now i just adjust the temp a little bit to get rid of the condensation on the outside and ride with it. I may bring it up to my dealer at the first service or I may find a way to fix it myself. Either way I'll have to agree that its slightly annoying. I wonder if its just an actuator not fully closing the defrost vent or the foam seal on the defrost door isn't that great. I wonder if an HVAC recalibration would fix it? I have noticed that if I put the mode selector in anything other than "up high" the fogging is worse, or if you have it in between settings its even worse than that.

 

I have auto a/c. Which one would help with the defroster? I have it set to the front vents only.

 

I uploaded couple pics. This is what I'm experiencing especially in the morning with front vents selected only and temp anywhere from LO to 75 degrees that tested so far.

 

Third option - foot/defroster auto mode. Standard is on. You would want that off so it doesn't blow to the windshield automatically when auto ac is on.