Touch screens in motor vehicles

[philvantwo]

Can't see the point of that Mick F, heater on in the car and the air con on?

[hamster]

It's as MickF says upthread - the cooling removes the moisture in the air, which thne means there is nothing to mist up with.
All building airconditioning systems work this way.

[Flinders]

As Hamster says, if you put on the aircon it takes moisture out of the car, so windows don't mist up as they can if you get into a car wet, and helps them clear faster in other circs.
In extreme circs (very cold, very damp inside car, or very hot) recirculating the air for a while can help, though it's best not to do it for too long, as fresh air is better for you!
I was stuck stopped on the M6 for four hours in a blistering heatwave (in a black car). I had to keep running the engine from time to time to cool the car down a bit, and because we were not moving, the cool fan itself couldn't do much even with the aircon; it was still suffocating heat. Eventually I twigged, and recirculated the air. It cooled faster, got much cooler, and I could leave the engine off for longer. Still used a fair bit of fuel though.

[Bonefishblues]

Modern ac systems work stuff out automatically and simply make the car a nicer environment to be in, why would one not have them on?

[Cyril Haearn]

Modern ac systems work stuff out automatically and simply make the car a nicer environment to be in, why would one not have them on?

They use energy

I open the window / sunroof if possible and dress up warm in winter

The fresh air outside is usually better than the air inside

[Bonefishblues]

Modern ac systems work stuff out automatically and simply make the car a nicer environment to be in, why would one not have them on?

They use energy

I open the window / sunroof if possible and dress up warm in winter

The fresh air outside is usually better than the air inside

That's the beauty of choice. If one changes ac filters, the air inside is usually better quality than the air outside.

ETA
The additional aerodynamic drag from having a window open goes a significant distance to spending the savings from having ac off.

[mjr]

The fresh air outside is usually better than the air inside

That's the beauty of choice. If one changes ac filters, the air inside is usually better quality than the air outside.

Does AC really clean up the air enough to compensate for drawing the air from nearer the exhaust of the vehicle in front? I'm not familiar with the research but it sounds like you are.

ETA
The additional aerodynamic drag from having a window open goes a significant distance to spending the savings from having ac off.

At high speeds, maybe, but then passive ventilation through the air intakes is usually sufficient, plus you can usually use the fans without the AC to use less energy. I tend to drive at low speeds with the windows slightly open (also better for hearing what's going on around you - I don't understand why most people who condemn headphone-using cyclists seem comfortable with motorists driving around with windows up and music on, sometimes even with headphones on) and when I reach the faster roads, wind the windows up and switch the fans on.

There's also an ethical question if AC makes the air inside "better quality than the air outside": is it fair for one to increase the energy use and thereby further reduce the air quality for everyone else in order to avoid the pollution one is contributing to? Seems like pollution evasion.

[Warin61]

It's as MickF says upthread - the cooling removes the moisture in the air, which then means there is nothing to mist up with.
All building airconditioning systems work this way.

No, not all. Some maintain not only the temperature but the humidity .. something between 40% and 70% is fair, better 50% to 60%. Of course you pay more for it.

Air con not only cools but heats - much quicker to use the air con in the car for heat when starting off on a cold morning.

[Bonefishblues]

The fresh air outside is usually better than the air inside

That's the beauty of choice. If one changes ac filters, the air inside is usually better quality than the air outside.

Does AC really clean up the air enough to compensate for drawing the air from nearer the exhaust of the vehicle in front? I'm not familiar with the research but it sounds like you are.

ETA
The additional aerodynamic drag from having a window open goes a significant distance to spending the savings from having ac off.

At high speeds, maybe, but then passive ventilation through the air intakes is usually sufficient, plus you can usually use the fans without the AC to use less energy. I tend to drive at low speeds with the windows slightly open (also better for hearing what's going on around you - I don't understand why most people who condemn headphone-using cyclists seem comfortable with motorists driving around with windows up and music on, sometimes even with headphones on) and when I reach the faster roads, wind the windows up and switch the fans on.

There's also an ethical question if AC makes the air inside "better quality than the air outside": is it fair for one to increase the energy use and thereby further reduce the air quality for everyone else in order to avoid the pollution one is contributing to? Seems like pollution evasion.

Air is drawn into the cabin at the level of the base of the windscreen. Window level, if you like.

I'm happy to live with the ethical dilemma and drive in an air conditioned environment, calculated to keep me more comfortable, alert, and as this morning, clear-screened from c30 seconds after switch-on due to the drying effect previously mentioned.

[mjr]

That's the beauty of choice. If one changes ac filters, the air inside is usually better quality than the air outside.

Does AC really clean up the air enough to compensate for drawing the air from nearer the exhaust of the vehicle in front? I'm not familiar with the research but it sounds like you are.

Air is drawn into the cabin at the level of the base of the windscreen. Window level, if you like.

Which if you look at the wind tunnel patterns of modern cars, is the air scooped up from the road at about exhaust pipe height.

There's also an ethical question if AC makes the air inside "better quality than the air outside": is it fair for one to increase the energy use and thereby further reduce the air quality for everyone else in order to avoid the pollution one is contributing to? Seems like pollution evasion.

I'm happy to live with the ethical dilemma and drive in an air conditioned environment, calculated to keep me more comfortable, alert, and as this morning, clear-screened from c30 seconds after switch-on due to the drying effect previously mentioned.

Isn't that pretty much deciding "[rude word removed] everyone else", rather than a dilemma?

[Bonefishblues]

Does AC really clean up the air enough to compensate for drawing the air from nearer the exhaust of the vehicle in front? I'm not familiar with the research but it sounds like you are.

Air is drawn into the cabin at the level of the base of the windscreen. Window level, if you like.

Which if you look at the wind tunnel patterns of modern cars, is the air scooped up from the road at about exhaust pipe height.

There's also an ethical question if AC makes the air inside "better quality than the air outside": is it fair for one to increase the energy use and thereby further reduce the air quality for everyone else in order to avoid the pollution one is contributing to? Seems like pollution evasion.

I'm happy to live with the ethical dilemma and drive in an air conditioned environment, calculated to keep me more comfortable, alert, and as this morning, clear-screened from c30 seconds after switch-on due to the drying effect previously mentioned.

Isn't that pretty much deciding "<i>[rude word removed]</i> everyone else", rather than a dilemma?

No, air is drawn in at the base of the windscreen. It is designed thus.

No, it's saying that I prefer to use the technology available to me to keep me as alert as possible on the roads, with the best visibility. That is why I wrote that. I think that alert drivers on the roads are a good thing. I remember driving before I had cars with ac. ac is better.

[mjr]

Air is drawn into the cabin at the level of the base of the windscreen. Window level, if you like.

Which if you look at the wind tunnel patterns of modern cars, is the air scooped up from the road at about exhaust pipe height.

No, air is drawn in at the base of the windscreen. It is designed thus..

Yes and air that arrives at the base of most windscreens starts off about the height of the exhaust pipe in front, thanks to the aerodynamic design of the front of most cars:

(source but there are plenty more similar)

[Bonefishblues]

Ah yes, using your picture, were you following a car closely at what, 60-70 mph, I see that would be the case.

That's not what happens in real life though. We do not follow closely. The air behind the car in front doesn't leave in a smooth lamina flow. It gets mixed up, and turbulent. We draw in, through intake and windows alike a mix of air. There is still merit in drawing from higher though, to avoid as best one can, the heavier particulates, some of which can be intercepted by car ac filters.

At slower speeds that aerodynamic discussion is moot.

[Cyril Haearn]

Why is it always an audi?

[Bonefishblues]

Sometimes the answer is "it just is"

Yours,

A parent