Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.


MadEngineer

4271 posts

Uber Geek

Trusted

#185877 8-Dec-2015 19:11
Send private message

Does anyone know the logic or reasoning behind this? When I start the car when it's been baking in the sun or there is otherwise a large difference between the outside and inside air it seems the climate control sets the air to recirculate. AC only seems to come on in the auto mode when the temp is set to the lowest position.




You're not on Atlantis anymore, Duncan Idaho.

Filter this topic showing only the reply marked as answer View this topic in a long page with up to 500 replies per page Create new topic
 1 | 2 | 3
sbiddle
30853 posts

Uber Geek

Retired Mod
Trusted
Biddle Corp
Lifetime subscriber

  #1443038 8-Dec-2015 19:18
Send private message

A/C is more efficient using air from within the car rather than outside. Most cars default to recirculate when you turn the A/C on.




richms
28168 posts

Uber Geek

Trusted
Lifetime subscriber

  #1443077 8-Dec-2015 20:08
Send private message

Once the car is cooler than outside, yeah. But initially when its 45+ degrees in the car, no. Im lucky enough to still have a slide control for it in my cars so can easily adjust it as I want.




Richard rich.ms

MadEngineer

4271 posts

Uber Geek

Trusted

  #1443082 8-Dec-2015 20:22
Send private message

sbiddle: A/C is more efficient using air from within the car rather than outside. Most cars default to recirculate when you turn the A/C on.

isn't the recommendation to open your window when driving around town and to use the ac with windows up when on the open road? it doesn't explain with the car would recirculate the air, especially when the AC isn't on and the car isn't moving

also recirculating the air eventually just makes the windows fog up when it's cooler outside




You're not on Atlantis anymore, Duncan Idaho.



richms
28168 posts

Uber Geek

Trusted
Lifetime subscriber

  #1443093 8-Dec-2015 20:38
Send private message

And let smelly diesel fumes in? No thanks. Recirc all the time except when the car is really hot from being parked.

Aircon will remove the moisture from the air, so fogging up shouldnt ever be a problem.




Richard rich.ms

alasta
6701 posts

Uber Geek

Trusted
Subscriber

  #1443118 8-Dec-2015 20:49
Send private message

If the car is scorching hot when I get in then I open the window for a few minutes to let out the excess heat, then roll up the windows and operate the air conditioning. As others have mentioned, recirculate will allow the AC to bring the cabin temperature down to a comfortable level more quickly but make sure you switch back to fresh air to avoid fatigue if you are on a long trip.

Wade
2225 posts

Uber Geek


  #1443119 8-Dec-2015 20:52
Send private message

richms: And let smelly diesel fumes in? No thanks. Recirc all the time except when the car is really hot from being parked.

Aircon will remove the moisture from the air, so fogging up shouldnt ever be a problem.


Agree with this.. On a hot day after car has been parked up i open windows and sunroof even just for a couple of minutes which gives the AC a fighting chance to bring temp down fairly quickly, by the time I'm out of the car park, windows back up, car almost pleasant, mind you I have tinted windows which definitely help the cause given black leather interior 

scuwp
3885 posts

Uber Geek


  #1443174 8-Dec-2015 21:55
Send private message

Because it's easier to cool a carload of air faster than to cool all the air in the atmosphere.  Initially it seems like a bad idea but it really does work once the initial cooling process starts.  




Lazy is such an ugly word, I prefer to call it selective participation



 
 
 

Cloud spending continues to surge globally, but most organisations haven’t made the changes necessary to maximise the value and cost-efficiency benefits of their cloud investments. Download the whitepaper From Overspend to Advantage now.
richms
28168 posts

Uber Geek

Trusted
Lifetime subscriber

  #1443179 8-Dec-2015 22:00
Send private message

I only ever put the window down to place my food order or to pay or collect it.




Richard rich.ms

mclean
581 posts

Ultimate Geek

Subscriber

  #1443344 9-Dec-2015 09:35
Send private message

To cool the car quickly you want the air coming out of the aircon to be as cool as possible. To do that you want the air entering the aircon to be as cool as possible.  So if it's cooler outside it's better to use outside air.  When it's hotter outside it's more efficient to use re-circulation.

(Slight simplification because the moisture content comes into it as well, but it doesn't make much difference.)

Batman
Mad Scientist
29760 posts

Uber Geek

Trusted
Lifetime subscriber

  #1443348 9-Dec-2015 09:40
Send private message

Maybe you should buy a Ford. (the Non Aussie ones). THey all default to using outside air no matter what you do the last time you used the car.

trig42
5809 posts

Uber Geek

ID Verified

  #1443355 9-Dec-2015 09:45
Send private message

All climate control A/C (usually the Auto button/Option in newer cars) will default to Recirc when first turned on/activated.
Mine pulls down the temp pretty quickly (Mazda3), then switches over to fresh air (usually after about 3 minutes).
If it doesn't switch to fresh air, then there is something wrong.

roobarb
653 posts

Ultimate Geek

Trusted

  #1443358 9-Dec-2015 09:47
Send private message

richms: I only ever put the window down to place my food order or to pay or collect it.


...or when the nice man in uniform asks you to.

MikeAqua
7773 posts

Uber Geek


  #1443360 9-Dec-2015 09:48
Send private message

I have read (but can't find again) a report on research undertaken in Europe where the authors concluded that people are more like to crash if they have their A/C set to recirc.  The author's believed that reduced oxygen levels affected concentration and exacerbated fatigue.  They recommended that A/C be designed to switch to fresh air after 15 minutes (or something like that) on recirc.




Mike


mdooher
Hmm, what to write...
1424 posts

Uber Geek

ID Verified
Trusted
Lifetime subscriber

  #1443378 9-Dec-2015 10:20
Send private message

Mine stays on outside air unless the air quality sensor detects low quality air, then it changes to recirculate


From the BMW Website:

 
Automatic Air Recirculation (AAC) delivers noticeably better air quality in the cabin of your BMW. The system recognises pollutants and contaminants in the outside air and removes them in a microfilter. Should the concentration of pollutants exceed a maximum level, the system automatically closes off air intake from outside and temporarily recirculates the air in the cabin.
The condensation sensor ensures that the windows of the vehicle do not become misted, even if humidity levels increase. In addition, the solar sensor measures the intensity and angle of the sun's rays, and the system automatically adjusts the air conditioner's performance to ensure a steady temperature is maintained. You and your passengers enjoy a steady cabin temperature, a clear view and excellent air quality at all times.


It does seem to work anyway




Matthew


MadEngineer

4271 posts

Uber Geek

Trusted

  #1444413 9-Dec-2015 11:47
Send private message

scuwp: Because it's easier to cool a carload of air faster than to cool all the air in the atmosphere.  Initially it seems like a bad idea but it really does work once the initial cooling process starts.  
this would make sense if a) the air con also came on with the recirculate function and b) if if was efficient to use ac, should I turn it on rather than open the windows. But generally it doesn't




You're not on Atlantis anymore, Duncan Idaho.

 1 | 2 | 3
Filter this topic showing only the reply marked as answer View this topic in a long page with up to 500 replies per page Create new topic





News and reviews »

Air New Zealand Starts AI adoption with OpenAI
Posted 24-Jul-2025 16:00


eero Pro 7 Review
Posted 23-Jul-2025 12:07


BeeStation Plus Review
Posted 21-Jul-2025 14:21


eero Unveils New Wi-Fi 7 Products in New Zealand
Posted 21-Jul-2025 00:01


WiZ Introduces HDMI Sync Box and other Light Devices
Posted 20-Jul-2025 17:32


RedShield Enhances DDoS and Bot Attack Protection
Posted 20-Jul-2025 17:26


Seagate Ships 30TB Drives
Posted 17-Jul-2025 11:24


Oclean AirPump A10 Water Flosser Review
Posted 13-Jul-2025 11:05


Samsung Galaxy Z Fold7: Raising the Bar for Smartphones
Posted 10-Jul-2025 02:01


Samsung Galaxy Z Flip7 Brings New Edge-To-Edge FlexWindow
Posted 10-Jul-2025 02:01


Epson Launches New AM-C550Z WorkForce Enterprise printer
Posted 9-Jul-2025 18:22


Samsung Releases Smart Monitor M9
Posted 9-Jul-2025 17:46


Nearly Half of Older Kiwis Still Write their Passwords on Paper
Posted 9-Jul-2025 08:42


D-Link 4G+ Cat6 Wi-Fi 6 DWR-933M Mobile Hotspot Review
Posted 1-Jul-2025 11:34


Oppo A5 Series Launches With New Levels of Durability
Posted 30-Jun-2025 10:15









Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.



Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.