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Does anyone use anti-mist liquids on their windscreens?
- Thread starter Tombri
- Start date
Billy Bumpsteer
Spa-Francorchamps
- Joined
- 12 Aug 2019
- Messages
- 339
Ya canny change the law of physics Jim...................... 
Quote from Tore on Rennlist;
The fogging has nothing to do with your HVAC servo motors, but is a completely normal phenomena in air cooled cars.
The engine lid opening allows for a lot of water to go into the engine bay when parked outdoors in rain. When the wet engine heats up after cold rainy night, huge amounts of hot humid air will be produced in the engine bay.
If you have the cabin temp set to anything above minimum, this extremely humid air will be sucked into the cabin from the engine bay through the heat exchangers. When this air hits the cold windows they immediately fog up due to the condensation on the cold surface.
The trick is to set the Climate Control temperature knob to minimum before turning on the ignition and keep it there for about 2-5 minutes after you have started driving in order to vent out all the humid air from the engine bay before turning up the heat. All air will then be drawn from the front fresh air intake, and have the same temperature as the windshield. No fogging.
Quote from Tore on Rennlist;
The fogging has nothing to do with your HVAC servo motors, but is a completely normal phenomena in air cooled cars.
The engine lid opening allows for a lot of water to go into the engine bay when parked outdoors in rain. When the wet engine heats up after cold rainy night, huge amounts of hot humid air will be produced in the engine bay.
If you have the cabin temp set to anything above minimum, this extremely humid air will be sucked into the cabin from the engine bay through the heat exchangers. When this air hits the cold windows they immediately fog up due to the condensation on the cold surface.
The trick is to set the Climate Control temperature knob to minimum before turning on the ignition and keep it there for about 2-5 minutes after you have started driving in order to vent out all the humid air from the engine bay before turning up the heat. All air will then be drawn from the front fresh air intake, and have the same temperature as the windshield. No fogging.
Billy Bumpsteer said:Ya canny change the law of physics Jim......................
Quote from Tore on Rennlist;
The fogging has nothing to do with your HVAC servo motors, but is a completely normal phenomena in air cooled cars.
The engine lid opening allows for a lot of water to go into the engine bay when parked outdoors in rain. When the wet engine heats up after cold rainy night, huge amounts of hot humid air will be produced in the engine bay.
If you have the cabin temp set to anything above minimum, this extremely humid air will be sucked into the cabin from the engine bay through the heat exchangers. When this air hits the cold windows they immediately fog up due to the condensation on the cold surface.
The trick is to set the Climate Control temperature knob to minimum before turning on the ignition and keep it there for about 2-5 minutes after you have started driving in order to vent out all the humid air from the engine bay before turning up the heat. All air will then be drawn from the front fresh air intake, and have the same temperature as the windshield. No fogging.
Tip top tip, thank for sharing.
Thanks Billybumpster.
That makes total sense to me.
So even with anti misting stuff applied to the screen you are likely to get misted windscreens (after the engine has got damp) - unless you apply your rules??
I love this forum for sensible and helpful hints like that.
Cheers. :thumb:
That makes total sense to me.
So even with anti misting stuff applied to the screen you are likely to get misted windscreens (after the engine has got damp) - unless you apply your rules??
I love this forum for sensible and helpful hints like that.
Cheers. :thumb:
nickjonesn4
Sao Paulo
- Joined
- 10 Aug 2017
- Messages
- 997
Billy Bumpsteer said:Ya canny change the law of physics Jim......................
Quote from Tore on Rennlist;
The fogging has nothing to do with your HVAC servo motors, but is a completely normal phenomena in air cooled cars.
The engine lid opening allows for a lot of water to go into the engine bay when parked outdoors in rain. When the wet engine heats up after cold rainy night, huge amounts of hot humid air will be produced in the engine bay.
If you have the cabin temp set to anything above minimum, this extremely humid air will be sucked into the cabin from the engine bay through the heat exchangers. When this air hits the cold windows they immediately fog up due to the condensation on the cold surface.
The trick is to set the Climate Control temperature knob to minimum before turning on the ignition and keep it there for about 2-5 minutes after you have started driving in order to vent out all the humid air from the engine bay before turning up the heat. All air will then be drawn from the front fresh air intake, and have the same temperature as the windshield. No fogging.
Superb tip!
pierrebear
Nurburgring
- Joined
- 27 Sep 2017
- Messages
- 387
Love that!!! Going to give that a go for sure. Whilst reading I could almost sense that this would be a completely polarising thread for all the different tribes of 993 owners out there: 'what's rain?"
Will Statt
Montreal
- Joined
- 28 Aug 2003
- Messages
- 525
Naaah.... just turn your air con on.... clears in seconds! :mrgreen:
Will Statt said:
Not correct.
To some extent, a cold evaporator will be able to remove some of the humidity in the air flowing through it. However, in the 993, the air condition evaporator will only affect fresh air from the front intake or recycled air.
If you have set the temperature control to anything above minumum, and it is cold in the cabin, both mixer flaps will be set to wide open to get air from the heat exchangers. The resirc flap will also be closed.
Any air conditioning will therefore not affect the humidity of the air at cold start at all.
The challenge in this is the cold windows and the hot air, resulting in water condensation, so having air con on to dry the fresh air is not necessary. The cold outside air have the same temperature as the window.
Cheers,
Tore
nickjonesn4
Sao Paulo
- Joined
- 10 Aug 2017
- Messages
- 997
ToreB said:
Pleased to confirm that this worked a treat this morning up here in Scotland. Was 4 degrees and I had no fogging following this method
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