[pb2]

Hi,

In past cars, I've always kept the air on recirculate, mostly to avoid allowing pollutants into the car and also because I've found that I get less dust on the dash if it's recirculate. The downside is that I always have to leave the A/C on, because otherwise it gets too humid inside.

Now that I have a BMW I'm intrigued by the auto-recirculate option. I have a few questions:
1. How does the auto-recirculate really work? How good are the filters when it's open? When does it close?
2. I've noticed that on occasion when I start the car it's gone back to venting. Does it do that if you leave the car on recirculate but not if you leave it on auto-recirculate?
3. Do you leave the A/C on or off when it's on auto-recirculate? I like leaving the A/C off, because my perception is that will help with gas mileage. Am I wrong here? Does it do the right thing with A/C and leave it off most of the time?

Thanks,
PB2

[Le Chef]

Using recirculate as actually the worst thing you can do. What you're doing is stopping fresh air getting into the cabin so building up CO2. You're also making the A/C work twice as hard to get rid of moisture in the air that you emit. The best options are "auto" on "auto recirc" on "A/C" on.

[Bimar]

Originally Posted by Le Chef

Using recirculate as actually the worst thing you can do. What you're doing is stopping fresh air getting into the cabin so building up CO2. You're also making the A/C work twice as hard to get rid of moisture in the air that you emit. The best options are "auto" on "auto recirc" on "A/C" on.

Its fine with windows open, nothing as bad as getting smoke from a truck in your cabin.

[Le Chef]

Originally Posted by inamik75

Its fine with windows open, nothing as bad as getting smoke from a truck in your cabin.

Why would you have your windows open and recirculation on at the same time? Makes no sense whatsoever.

[clivem2]

On recirc I get a dry throat after a short while.

[Bimar]

Originally Posted by Le Chef

Why would you have your windows open and recirculation on at the same time? Makes no sense whatsoever.

Because u have missed the point, try driving behind a diesel truck with recirc off u will inhale those fumes first hand, with recirc on and windows lowered you get free flowing air in the cabin at speed. Very logical if are not a fan of AC and not keen on inhaling co2. Recirc fan needs to be off!

[TogMogX3]

Bonkers! Bleeding bonkers!

I know that it takes all sorts to make a world but whatever are some people thinking about?

[Le Chef]

Originally Posted by inamik75

Because u have missed the point, try driving behind a diesel truck with recirc off u will inhale those fumes first hand, with recirc on and windows lowered you get free flowing air in the cabin at speed. Very logical if are not a fan of AC and not keen on inhaling co2. Recirc fan needs to be off!

Maybe airflow and aerodynamics are different in Nairobi but in the rest of the world with windows open all you will do is get bad air and diesel fumes coming into the vehicle. If you drive with the windows closed and recirc on auto you won't have that problem...

Check your handbook!

[Bimar]

Originally Posted by pb2

Hi,

In past cars, I've always kept the air on recirculate, mostly to avoid allowing pollutants into the car and also because I've found that I get less dust on the dash if it's recirculate. The downside is that I always have to leave the A/C on, because otherwise it gets too humid inside.

Now that I have a BMW I'm intrigued by the auto-recirculate option. I have a few questions:
1. How does the auto-recirculate really work? How good are the filters when it's open? When does it close?
2. I've noticed that on occasion when I start the car it's gone back to venting. Does it do that if you leave the car on recirculate but not if you leave it on auto-recirculate?
3. Do you leave the A/C on or off when it's on auto-recirculate? I like leaving the A/C off, because my perception is that will help with gas mileage. Am I wrong here? Does it do the right thing with A/C and leave it off most of the time?
Thanks,
PB2

Auto recirc is sensor driven so the car decides for you what is good of bad air to let in automatically into the cabin. I personally dont use it nor AC at the same time I prefer free flowing air with my windows partially down at highway speeds with recirc permanently on and the Fan on off, but that's just me. The X3 has a microfilter removes dust and pollen and an activated-charcoal filter removes gaseous pollutants from the outside air that enters the vehicle. (so they claim)

Originally Posted by Le Chef

Maybe airflow and aerodynamics are different in Nairobi but in the rest of the world with windows open all you will do is get bad air and diesel fumes coming into the vehicle. If you drive with the windows closed and recirc on auto you won't have that problem...

Check your handbook!

Given this is a global forum, your assumptions are flawed firstly not all BMW have auto recirc including the X3 for different parts of the world get different specs of the same car or they are options and secondly you have assumed the rest of the world has bad air, different parts of the world and even in the same city have different levels of air quality, in either case one needs to speak for themselves. I choose to have free flowing fresh air at highways speeds with my windows partially lowered or sunroof partially open if weather permits, it is my choice.

Pics of the different climate controls on the X3 with auto recirc and without.