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Author Topic: Why does the car back window fog up first?  (Read 12457 times)

Offline OldMan

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Why does the car back window fog up first?
« on: 17/06/2004 04:33:08 »
My brother would like to know why the back window of the car is always the one to fog up first, even when there isn't anyone back there breathing heavly or getting hot and steamy.

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« Last Edit: 30/06/2004 08:41:56 by Exodus »


 

Online chris

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Re: Why does the car back window fog up first?
« Reply #1 on: 17/06/2004 08:21:04 »
Great question. I'm going to have to guess :

The rear window is the last one to warm up and has no airflow hitting it from the car driving along (unless you go everywhere in reverse). Also through-draft in the car will carry everyone's moisture-laden breath towards the back where it condenses on the cold rear window.


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Offline neilep

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Re: Why does the car back window fog up first?
« Reply #2 on: 17/06/2004 11:53:38 »
Perhaps the front window is still being blasted with air, even though you may not have the fans on ,I still find there is a latent draft....and in any case the rear window does not receive direct fanning anyway.

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Offline OldMan

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Re: Why does the car back window fog up first?
« Reply #3 on: 18/06/2004 03:36:05 »
Yeah I thought it might be something like that as well but it also seems to be the case most of the time when the car isn't being driven so the airflow should be the same. Don't know sure has me baffled.

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Offline gsmollin

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Re: Why does the car back window fog up first?
« Reply #4 on: 18/06/2004 13:25:30 »
The windshield is fitted with large air vents that cause an air movement across it whether or not the car is moving, or if the blower is operating. The back window has no such vents, so it fogs up first. If you doubt the effectiveness of these vents, you can always stuff rags in them to see what happens. Personally, I already know, because for years I drove old Volkswagen Beetles (the Type 1, not that Jetta they call a Beetle now), which had almost no air flow across the windshield, and they fogged up almost instantly.
 

Offline neilep

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Re: Why does the car back window fog up first?
« Reply #5 on: 18/06/2004 18:57:16 »
.....failing the rag experiment, you could always hack the top of the car off and turn it into a convertible....problem solved !!:D

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Offline tweener

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Re: Why does the car back window fog up first?
« Reply #6 on: 21/06/2004 21:36:23 »
I drove a REAL Volkswagen for many years and can attest to the fact that the windshield can fog up instantly at some of the most inopportune (and unexpected) times.  I had pretty good airflow too - none of the vents had any hoses behind them, so everything was open to to front, which is open to the outside.  I also had a large hole in the floor that was another opening to the outside.

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Offline OldMan

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Re: Why does the car back window fog up first?
« Reply #7 on: 23/06/2004 04:31:42 »
God bless the old volkswagen didn't they just rock. We had one for many years, pity we sold it I would have liked to drive it and it was in such good condition as well.

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Offline neilep

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Re: Why does the car back window fog up first?
« Reply #8 on: 23/06/2004 12:45:01 »
yep....I think the VW Beetle world took a step back when they introduced the new one....especially, as I understand it, that the original Beetle sales were still doing very well, and that from an economic point of view there was really no need for a change, and that it was purely for the sake of aestheticss that the new one was launched.

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Offline eddirichard

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Re: Why does the car back window fog up first?
« Reply #9 on: 23/06/2004 22:40:30 »
I have a 95 Mercury tracer whose front windshield always fogs up during rainy days. Can anyone tell me how I can get rid of the problem? It sometimes happens when I'm doing 55mph on the freeway!
 

Offline OldMan

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Re: Why does the car back window fog up first?
« Reply #10 on: 24/06/2004 03:52:04 »
Some people may not agree at first but trust me this works well. Stick your airvent control so that it is taking the air from the outside and have it turned onto heat. Should work like a charm.

The way I figure it is with having it on the outside air, and blowing on the windscreen of course, the humidity should kind of equalise.

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Offline neilep

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Re: Why does the car back window fog up first?
« Reply #11 on: 24/06/2004 12:41:28 »
I agree with Tim....and I know this might be a silly question but do you have air con ?...if so, put it on...I keep mine on all the time, doesn't matter if it's putting out cold or hot, and it really doesn't use up that much petrol/gas but it should help......of course...if you haven't got air con forget it.

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Offline eddirichard

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Re: Why does the car back window fog up first?
« Reply #12 on: 25/06/2004 17:37:06 »
Hey it works!
 

Offline gsmollin

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Re: Why does the car back window fog up first?
« Reply #13 on: 25/06/2004 18:44:08 »
quote:
Originally posted by neilep

yep....I think the VW Beetle world took a step back when they introduced the new one....especially, as I understand it, that the original Beetle sales were still doing very well, and that from an economic point of view there was really no need for a change, and that it was purely for the sake of aestheticss that the new one was launched.

'Men are the same as women...just inside out !'



The Type 1 was essentially outlawed by tail-pipe emission standards. Volkswagen had been keeping up for a while, but it involved a lot of compromises in the engine design, and meeting future standards was going to involve a lot of expense. Management at Wolfsburg decided to adopt a radical design from the Audi division- the front-wheel drive-train with transversely-mounted, water-cooled engine. This solved so many problems that it has since become the defacto design for almost all passenger automobiles. Nevertheless, I too mourned the passing of the Type 1. I owned five of them. However, I never missed the lousy defroster and heater. The tooling was exported to Brazil, where Type 1's were manufactured until just recently.
 

Offline tweener

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Re: Why does the car back window fog up first?
« Reply #14 on: 26/06/2004 03:11:20 »
They were also manufactured in Mexico City for many years, shutting down only recently.

I still own my old Bug - it is sitting in the barn waiting for me to get around to restoration.  We owned an old Bus for a while.  That was a great vehicle too.  I'm sorry now we sold it.

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Offline neilep

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Re: Why does the car back window fog up first?
« Reply #15 on: 27/06/2004 16:06:47 »
....they just could not make the 'Herbie' films with the new incarnation.....could they ?

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Offline gsmollin

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Re: Why does the car back window fog up first?
« Reply #16 on: 30/06/2004 00:35:34 »
quote:
Originally posted by tweener

They were also manufactured in Mexico City for many years, shutting down only recently.

I still own my old Bug - it is sitting in the barn waiting for me to get around to restoration.  We owned an old Bus for a while.  That was a great vehicle too.  I'm sorry now we sold it.

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Ah yes... Every time I hear the Eagles play "Take it Easy", I am reminded of a young girl with long red hair, a hippie dress, driving a VW microbus, one afternoon on July 4th weekend. I was hitch-hiking to San Francisco, and she picked me up in Sacramento.
 

Offline tweener

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Re: Why does the car back window fog up first?
« Reply #17 on: 30/06/2004 02:56:56 »
And.....???

You can't just leave us hanging like this!

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Offline neilep

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Re: Why does the car back window fog up first?
« Reply #18 on: 30/06/2004 03:14:10 »
.......yes Gsmollin.....what are you playing at here ?....you just can't leave us out in the cold without saying what occurred next eh ?........c'mon...spill the beans !!....we want to be picked up too, so what happened to you ?......:D;)

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« Last Edit: 30/06/2004 03:14:45 by neilep »
 

Offline gsmollin

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Re: Why does the car back window fog up first?
« Reply #19 on: 30/06/2004 17:47:15 »
It's part of a much longer tale about my summer on the road. I don't believe it's ever been told in full. Anyway, I was on my way to San Francisco. Things hadn't been going too well. The night before I had slept in a ditch just west of Salt Lake City, on Route 40. At sun-up I got up too (the accomodations were poor), and decided to try my luck, once again. My luck was changing. The first car was a guy moving from Wisconsin to Sacramento. He picked me up, and we bumped along at low speed across Utah and Nevada. He had every cubic inch of his car crammed with his possessions, and was towing a trailer. Somewhere in the desert in Nevada, we stopped for gas. I went into the men's room, and when I came out, the gas station attendant was disconnecting the trailer. The guy told me that the differential was leaking oil. I was so bent out of shape, since this was a good ride! I demanded to see the leak. The attendant showed me the oil coming down the side of the differential. It was full of dirt, not a fresh leak. This was one of those desert scams, where they rip your car apart, and want thousands to put it back together! I told that clown to take the car off the jack, and told my ride it was no problem, just have it looked at in Sacramento. We got back on the road and continued west. We crawled over Donner's Pass, and coasted into Sacramento. The guy told me he knew of a good place to catch a ride and dropped me off there.

This corner was jammed with hitch hikers, more than I had seen on my whole trip. I was afraid I would be there for days, but was I wrong. Every couple of minutes, a car would stop, and the driver would yell, "I've got room for three to Davis.", or something like that. Most people were going to Davis, where there was a campus for University of California. About 20 minutes later, I was at the head of the line, when the faded green VW minibus pulled up. A red-headed hippie girl yelled, "I've got room for six to San Jose!" I had found my ride.

I got into the front passenger's seat, and the other five got into the back. They all knew each other, and were going to Davis. We dropped them off at Davis, and continued to San Jose, via San Francisico. The girl and I talked for a while, then she began to tell me about her situation. She had just been set free by her "old man". She said it was so strange being alone, since she had always been with her old man, for years, I think. He just got up one day, and left for Boston. So, would I mind being her old man for the July 4th weekend? She was going to a commune in San Jose, and would take me back to SF on Monday. This was the end of a long day, with a bad night's sleep, and I was being asked to marry her for the weekend? Well, I took a long look at her. She was about 20 years old, 5 ft 3 in, maybe 110 pounds. Had red hair down to the small in her back; it had a slight wrinkle in it. She was wearing this peasant sun dress, which I didn't particularly like, but I was removing it in my mind's eye anyway. I decided that my luck had changed for the better, after all.

That's all of that story I have ever told. There aren't any details about the weekend in San Jose for publication. If there were, I couldn't relate them here anyway.
 

Offline neilep

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Re: Why does the car back window fog up first?
« Reply #20 on: 30/06/2004 18:06:12 »
quote:
Originally posted by gsmollin


That's all of that story I have ever told. There aren't any details about the weekend in San Jose for publication. If there were, I couldn't relate them here anyway.



YES YOU CAN !!...but we won't push you for more !!..sounds like a fun time !!...

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Offline tweener

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Re: Why does the car back window fog up first?
« Reply #21 on: 01/07/2004 03:33:36 »
Great story!!  YOU CAN relate the details here.

Obviously some of us have been married waaayy tooooo looonnng!

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Re: Why does the car back window fog up first?
« Reply #21 on: 01/07/2004 03:33:36 »

 

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