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Old 28th September 2007, 10:13   #1
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Default Fog on windshield - dangerous and scary

I've been encountering a problem with fog forming on my windshield, and it's quite scary, especially when trucks pass with their lights set inevevitably on high beam.

There were a few threads on fog in this forum, but nothing I found regarding windshields. There are some resources on the internet talking about avoiding fog, but I wanted some advice in the Indian context.

If fog forms on the inside of a vehicle, it's normally easy to get rid of it by turning on the heat, or the A/C.

However, I've had the opposite problem. Let's say I head to somewhere in the evening, driving for 30-45 minutes with A/C on mostly at recirculate (to avoid outside dirty air). I park for 3 hours. When I head out, there's fog forming on the outside of the windshield.

Since the fog is basically water on the windshield, I turned on the wipers. That helps for about a half second, by which time more fog forms, and a truck comes by with its high beams, totally lighting up the fog and blinding my view. It doesn't really seem to help to set the wipers faster either.

It seems as if there's this weird layer of permanent frost/fog on the windshield, no matter if the wiper just wiped it. (I did clean the windshield before heading out.)

I also attempted to set the HVAC to A/C on, full high heat, outside air, full blower, defrost mode (air to the windshield). I also tried full cold, and somewhere in the middle, and also A/C off with outside air, but to no avail.

Nothing really worked, and I turned off to a lesser trafficked road, and kept the wipers on slow, and turned them on faster when the occasional truck came by.

When I came back to my starting point, I noticed a great amount of water condesnsed on the roof of the car (Innova) plus on the windshield where the wiper doesn't reach.

How do other thbp'ers handle such night driving?
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Old 28th September 2007, 10:32   #2
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Switing on cold AC on such conditions will make it worse. Increase the temperature control towards hot, put the HVAC control in defog mode and increase the blower speed. This has worked for me.
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Old 28th September 2007, 10:48   #3
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Default Mist

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Originally Posted by prskumar View Post
Switing on cold AC on such conditions will make it worse. Increase the temperature control towards hot, put the HVAC control in defog mode and increase the blower speed. This has worked for me.

Bottom line is to even out temperature differences between outside and inside.
I have tried what you said. It does not work. Only yesterday i was constantly fiddling with the AC settings between hot and cold to get the right temp to get rid of the mist on the outer side of the windshield.
Only wipers would work then it reforms almost immediately.
I have not had an instant solution for this.
However i have found that opening windows momentarily along with changing AC recycle to let in fresh air
Solves the problem instantaneously.But cant drive with windows in the rain can we?
The only option is to leave a 2 mm gap in the glass on the top so that there is a seepage of air from outside at the cost of letting in polluted air.

What scares me more is all that dust and grime settling on the dashboard and upholstery!!
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Old 28th September 2007, 11:10   #4
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You need to use the defogger setting on your AC control that's all; if that doesn't work sounds like you need to ask your workshop to check it out. Alternating between hot & cold settings will not get rid of the misting, you need to use the defogger setting
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Old 28th September 2007, 11:26   #5
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Quote:
Originally Posted by caliper View Post
It seems as if there's this weird layer of permanent frost/fog on the windshield, no matter if the wiper just wiped it. (I did clean the windshield before heading out.)
I too have encountered the same problem whenever i have taken out the Innova
I too have encountered the same problem whenever i have taken out the Innova... Specially when it rains, and during night driving i find the windshield to be very dirty and it becomes very difficult to see when light from opposite traffic hits the windshield...
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Old 28th September 2007, 11:28   #6
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Do you live in a coastal city? If yes, this thread (Unclear Glass during Rain) should be of some help
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Old 28th September 2007, 11:36   #7
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I too have faced this problem after the same sequences of car usage as told by Caliper.

But surprisingly this stopped happening after I started using a proper windshield washer. One shot off the nozzles and the wiper, the fogging does not happen.

Before that, the fogging used to occur again and again while I was using plain water and soap.


EDIT: just saw theMAG's post and the link given. the explanation holds good in that post.

Last edited by gbpscars : 28th September 2007 at 11:40.
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Old 28th September 2007, 11:54   #8
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This is pure condensation, and it has happened with me in my Esteem in Delhi. Basically happens due to the drastic difference between the outside temperature and in the car and more so in rains because its already humid outside.

Nothing except for the wipers seemed to have worked for me. Opening the windows was out of question because it was raining heavily. Else, I think it would have helped.
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Old 28th September 2007, 11:56   #9
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Quote:
Originally Posted by theMAG View Post
Do you live in a coastal city?
Well... I Dont...
Setting the AC to warm temperature might solve the problem but then it would get warm inside the vehicle too right... not too comfortable.
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Old 28th September 2007, 12:02   #10
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Quote:
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Well... I Dont...
Setting the AC to warm temperature might solve the problem but then it would get warm inside the vehicle too right... not too comfortable.
Dear Jay,

That was intended for caliper
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Old 28th September 2007, 12:24   #11
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Dear Jay,

That was intended for caliper
I know that Maggie, i just wanted a solution for people not living in coastal cities hence i mentioned that.
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Old 28th September 2007, 12:33   #12
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Quote:
Originally Posted by theMAG View Post
Do you live in a coastal city? If yes, this thread (Unclear Glass during Rain) should be of some help
No, north India. But due to the water standing in the rice fields, it's probably the same thing in terms of humidity while highway driving.

I'll check out the link.
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Old 28th September 2007, 13:00   #13
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Shouldn't the front windshield also come fitted with defogging coils like the rear one? Of course they'll have to be thinner and finer to prevent view blockage. Some cars already have that feature.
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Old 28th September 2007, 13:09   #14
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Shouldn't the front windshield also come fitted with defogging coils like the rear one? Of course they'll have to be thinner and finer to prevent view blockage. Some cars already have that feature.
Which cars? Any sold in India? The fact is, car manufacturers do listen to feedback from customers. For example, the top-model Innova used to only come in 7-seater, and now it's available in 8. So I hope they would listen to feedback regarding window fogging problems.
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Old 28th September 2007, 13:20   #15
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Originally Posted by suman View Post
You need to use the defogger setting on your AC control that's all; if that doesn't work sounds like you need to ask your workshop to check it out. Alternating between hot & cold settings will not get rid of the misting, you need to use the defogger setting
My apologies, I meant DEMISTER setting, NOT defogger (there is no defogger position on the AC control )
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