Aircon re-circulate/fresh air in cabin?

[CMF_Faheyk1981]

Hi,

I drive a K11 Nissan March 1995 and wondered, does anyone know if you keep the vents on re-circulating air or fresh air, do you get/keep colder air in the cabin by selecting either of these options?

Does it make any difference at all when using the aircon in your car?

Thanks,
Kevin.

 

[CMF_asdame]

i think it would logically be quicker to cool the cabin if you close windows and recirculate air whilst the aircon is on cos the evaporator would then be cooling pre-cooled air that exited the vents therefore getting colder and colder more rapidly

 

[CMF_david (2)]

for me i recommend fresh air with driver window down for about 30 seconds...until the 50 degree c air has left the car.
Then close windows and switch to recirculate with max ac. This setting definitely results in cooler ac than leaving it on fresh. Can really tell the difference on 40 deg days!!

 

[CMF_Micra_King]

re-circulating makes it get cooler than fresh as its cooling the same air and not having to cool warmer fresh air all the time and you dont get all the fumes sucked in from outside like diesel fumes and so on.

 

[CMF_Bishop]

I seem to remember a technique mentioned in several owners manuals, setting on recirculate air, with one or two windows open about an inch or less.

From memory that will get the hot air out of the car fastest, and I think it was something I used to do a fair bit back when I owned cars with air con, and parked in open car parks.

 

[CMF_bongo bus]

the only problem with recirculating the air on long drives is that the longer the same air recirculates the more likely you are to start feeling sleepy, cause you are breathing less and less oxygen.
that is one of the key causes of micro sleep.

 

[CMF_mycra]

bongo bus WROTE:

"the only problem with recirculating the air on long drives is that the longer the same air recirculates the more likely you are to start feeling sleepy, cause you are breathing less and less oxygen.

that is one of the key causes of micro sleep.

true...then again recirculating is just moving air faster and without cooling eventually it'll get just as hot as ambient. thats why during hot days you turn on your fan....just the area its blowing is cool but everywhere else it actually hotter. i did a experiment on this at uni.

 

[CMF_Micra_King]

mycra WROTE:

"bongo bus WROTE:

"the only problem with recirculating the air on long drives is that the longer the same air recirculates the more likely you are to start feeling sleepy, cause you are breathing less and less oxygen.

that is one of the key causes of micro sleep."</div>

true...then again recirculating is just moving air faster and without cooling eventually it'll get just as hot as ambient. thats why during hot days you turn on your fan....just the area its blowing is cool but everywhere else it actually hotter. i did a experiment on this at uni.

You missing something here. The cars aircon is working on recirculating and it gets colder unless you switch off the AC button and just have the fan working. On fresh the A/C has to cool the air as it comes into the cabin where on recirculating its sucking back in the air that's already in the car and cooling it again and again which makes the temps go down more.

 

[CMF_mycra]

mmmm my bad.

 

[CMF_Faheyk1981]

Thanks to all for your comments.

 

[CMF_mipcar]

It will get stuffy if you keep it on closed circuit too long. I use re-circulate to get the temps down then set the control midway between closed and fresh, that seems to work ok for me.

Also when I get in the car first off I put the aircon on but drive a k or two with windows open to suck out some of the the hot air.

 

[CMF_Terry1981]

Keepin the circuit cools the car cooler fater that keepin it open..
1 draw back I ahve noticed keeping it open is when fresh air enter the cabin along with the air con it tends to pick up small dust particles & other stuff along the way and finally get diposited in your cooler & also some on your self too along with the A/c.

So would not recomend it keeping open..

Also a trick that i figured out on very hot days is that even though u switch the A/c on it does not get cooled enough for your expectations???

So when you come across this problem switch of the car pop the hood and pore some water on the Condencer Unit which is located in the car and then switch the A/c back on & u will feel the quick differance ...

Cheers ......

 

[CMF_bongo bus]

its cause you are dropping the head pressure in the refrigerant.
if thats happening take it to the aircon guy cause you may be experiencing a slight blockage in the refrigerant circuit. which can cause damage in the a/c compressor.