Defogging in humid weather

Can someone please post the best method of defogging ones' winshield in humid (hot) weather? I put my defogger on highest possible fan...and the fog from the inside of the window goes away completely. However,
the winshield is still fogged up from the outside and refuses to go away without the use of my wipers. Even then it does not go away completeley (still a thin layer of fog)...and then returns fully in a few seconds unless I keep my wipers on (even though its not raining). I never had this problem before with my other cars. It only seems to be happening on my new 2005 Honda Acoord. I spoke to a friend who also purchased the same car...and he complaind of the same problem. Neither blowing cold or hot air with or w/o the A/C seemed to get rid of the outside fog. Any suggestions? Anybody else with the same problem?
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Yes, but it only happened to me once. I turned on my wipers to get rid of it. Not sure how to prevent this from happening, except to possibly turning the a/c a little warmer? It only happened once on my '05 Accord so I never tested this method. Since it is happening on the outside I can only assume it is the colder air from the a/c that is chilling the windshield, creating this effect. Could this be the reason? I'm not sure but can't imagine what else it could be.
-Dave
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Happened all the time in my '93 Civic EX. Frequency likely depends on what the dew point is typically like when you're driving, so it'd be sensitive to location. I was mostly around Boston and Cincinnati (and sometimes en route from one to the other, obviously), both of which tend to be humid.
I admit that the first time it happened it took me a couple of minutes to realize that the condensation was on the outside of the window. It was the first day I had the car and I thought at first that maybe I had a bad radiator and coolant vapor was leaking into the cabin - a problem I'd had with an ancient Buick I used to drive (somewhat affectionately known as the "Chernomobile", in honor of its senendipitous fog-machine effects).

That should fix the problem. Reducing the fan speed once the inside of the windshield is clear may also help. Turning the defogger on full blast directs lots of cold air at the inside of the windshield, which tends to cool the outside of the windshield, which causes condensation. Simple, really.
Turning the air temp up will reduce the cooling effect, and unless you're driving through a tropical monsoon shouldn't bother you. Using a slower fan speed will reduce the forced convective cooling of the inside of the windshield and allow the outside to retain more heat.
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snipped-for-privacy@gmail.com wrote:

    All the Hondas I have owned do this. The outer side of the windshield gets cold enough to drop below the dew point of the ambient air, and water condenses at the lower edge outside. Lack of heat coming off the engine to the same area also allows snow and ice to build up there in the winter. My old Pinto never had either problem. bob
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Is this a design flaw by Honda? I see it as a safety issue...and if it is a flaw they should issue a recall, shouldn't they?
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snipped-for-privacy@gmail.com wrote:

Why is it a safety issue?
If moisture is on your windshield, use the wipers to wipe it off.
Or do you expect life to be perfect in all ways?
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It's not a design flaw. Honda engineers have no control over the elements. The problem is related to conflicting temperatures(interior vs. exterior) and humidity. My son was just complaining about this exact same issue yesterday after having driven his 1990 Nissan 300ZX in extremely humid conditions. I've experienced this same problem with most all of my cars at one time or another. I've just always relied on the windshield wipers--and it will eventually clear up and stay clear during your drive. It doesn't usually plague you for very long after you've ran the wipers for a while.
Ron M.
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I have to agree..Just bought a CRV with 300 miles on it. Night time 68f 90% humidity, no problem with clearing inside but outside had to use wipers and it still left a film which built up right away with moisture. Cleaned window on outside and inside with good glass cleaner to no help. Tried heat and cold and all in between. The wipers need to run almost constantly, hell I thought there was a leak in engine compartment... Never had this problem with other vehicles on same night- Jeep Cherokee and Taurus..... Sounds like a safety issue to me....Something is not right.....
Thanks Tom

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wrote:

Its not a safety issue at all. when you use your AC on cool to clear the glass, you're clearing the inside, by removing the internal humidity. however, the glass is cold enough to drop below the external dew point. Solution - heat the windscreen up - that is what the defrost setting on your car heater is for!. Warm the glass, its not a proble. My experiance is that american vehicles (such as the taurus and jeep0 tend to have thinner and/or less insulating glass, so the gradient between in and out isn't so bad.
I have, however, had this problem on EVERY SINGLE CAR i've ever owned, one time or another - and most of them don't and never have had, AC. in those cases, you run the engine fora bit, get the inside warm, then stick the wipers on intimittant, or use the manual single-sweep when needed..
What is all this obsessing with 'this sounds like a safety issue' - even *IF* it was, there would be no recall, since a solution (THE WIPERS) are already included into the design of the car.

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I agree with your comments on heat. My point is I tried with the heat with and without recirc. and the problem was still there... I never noticed this before with other vehicles....
Tom

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TF wrote:

The issue with the "safety" is that it seems others, not just myself, experience much worse windshield fog on Honda vehicles than other models/makes. I drove a Camry, Maxima, and Caravan Minivans...and don't recall a prob with the windshield fogging in any of them. While I don't disagree with your assursion that it is cause by outside elements, it still seems odd that Honda vehicles seem to be reacting worse than others. The wipers don't help too much especially when driving on 2-way roads, at night. The oncoming headlight glare illuminates the fog and makes it hard to see even with the wipers on. Hence, the saftey issue. It is possible that the Honda glass is thicker (it does seem to be very thick..never compared though) and therefore the problem is somehow exaserbated. I tried warming up the windshield (set my inside temp to 77-78) but it actually worstened the problem.
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On 29 Aug 2005 09:14:29 -0700, snipped-for-privacy@gmail.com wrote:

As i said, i've had it happen in every vehicle i've driven (within reason). ESpecially when i was in the UK, as its humid, often cold, and AC has only recently become standard.
It's hapened on golfs, volvos, austin/MGs, friends fiat panda was very bad at doing it (but it had a weak heater), although the worst of the lot was a 98 ford Fiesta zetec.
That being said, it does happen here in georgia too - i've had it happen with my 88 civic, my 87 caravan, and a 96 T+Ci've been passengers in friends vehicles when its happened to them - 88 silverado, 2001 venture, and an 05 camry. Its just how it goes. trigger the wipers when its a problem - its just like light rain/drizzle, (which is effectively what is is) and deal with it.
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snipped-for-privacy@gmail.com writes:

It may simply be that (some) Hondas leak less hot air from the engine compartment out onto the base of the windshield, so it's easier to chill the exterior of a Honda windshield.

Are you sure? Heating the windshield should not increase condensa- tion. I can think of two explanations: it didn't actually aggravate the condition (you imagined it, or it only worsened during the time it took for the windshield's outside temperature to rise), or your car has an actual defect and your problem *isn't* simple atmospheric- moisture condensation. A leaking heater core, perhaps.
I can imagine that you might be driving under conditions where it's not raining, the dew point is at or above 78 degrees[1], and there's no other source of heat for the windshield exterior (it's not sunny, for example), and so you might still get some condensation even with the temperature set that high. (And may I say I'm glad I'm not living under those conditions. Yuck.) But raising the temperature from the minimum setting couldn't cause *more* condensation of atmospheric moisture.
1. Actually, I bet the exterior of the windshield has to be somewhat below the dew point for condensation to occur, if the vehicle is in motion; otherwise air movement will allow the air flowing over the windshield to be somewhat supersaturated with moisture. So the dew point would probably have to be somewhat over the cabin temperature. I don't know enough about water-vapor physics to guess by how much, though.
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