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      01-10-2011, 12:37 PM   #1
w01f
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Recirculation-air Mode

Hello,

I have a problem whereby the permanent recirculated-air mode doesn't work... Let me explain:

My BMW 3-Series Exclusive Edition has a feature called Automatic Air Recirculation Control (AUC) / recirculated-air mode whereby if the air outside has an unpleasant odour or contains pollutants, the outside air supply can be shut off.

There are two modes - automatic and manual, based on repeatedly pressing a button to chose the operating mode.

LED off: outside air is constantly entering the car.

Left-hand LED on, AUC mode: a sensor detects pollutants in the outside air and shuts it off automatically.

Right-hand LED on, recirculated-air mode: the ambient air supply is permanently shut off.

If I leave the right-hand LED on, I would expect no unpleasant smells would enter the car, such as driving though smoke from a fire, but I find in my car this more often than not doesn't work.

I took it to the garage and they said permanent doesn't mean permanent if certain environment variables are met, such as cold weather, and that outside air is then let into the car, even though I've chosen the right-hand LED.

Has anyone else on this forum had the same problem? Is it normal?

Thanks in advance for your help.
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      01-10-2011, 01:40 PM   #2
F104
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if the RH LED is on (i do wish BMW would make that one red..) there's a motorized valve which closes off outside air going into the car. The valve takes a bit of time to close, and on recirculation the inside air does not get refreshed and will start to.. hmm.. stink. To my knowledge there's nothing that overides the 'recirculation' position - that's why i'd like to see a red LED

But it might be as well a micro culture growing on your airco cooler - just make sure you clean it once a year at least. If you have a micro garden on it it will be more obvious when on recirculation
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      01-10-2011, 02:14 PM   #3
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Thanks for helping to at least confirm what I thought should be happening.

Could anyone else also chip in to say this is the case for you too please? I'm trying to build up evidence so that BMW stop fobbing me off and confirm there is a fault with my car.

So, my car is brand new (Dec 2010) and the recirculation hasn't worked properly from the start, so even with the right-hand led switched on in plenty of time before the offending odour reaches my car, the smells such as bonfire smoke still blow in from the vents.

BMW tell me that sometimes the permanent mode let's air in depending on undisclosed environment variables, which I think isn't true, hence this post to find out the truth!
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      01-10-2011, 02:52 PM   #4
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It's a simple two minute job to remove the filter. 6 M8 screws. There's two inlets underneath, probably for LHD/RHD cars. The inlet to the fan will be obvious. Just hit the recirculation button and you can see the valve closing. If it doesn't close you have a problem. This is also where i spray my airco cleaner into
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      01-10-2011, 04:34 PM   #5
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I don't think the auto recirc mode is meant to block 'quick' events such as driving through a bit of smoke etc.

It doesn't detect 'odours' either, just particles in the air AFAIK.

I would say its meant for heavy air pollution that is present for a few minutes.

If i'm behind a smokey old car , then putting manual recirc on does seem to stop the fumes after a few seconds. Auto recirc never seems to do anything!
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      01-10-2011, 05:10 PM   #6
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Yes I have experience of this...with BMW, their technical department's in the UK and in Germany, along with the designers of the system. I even had a live data logger sent over from Germany, was fitted to my car and we recorded the functions over a week. I also took video clips of the actions and sent the files back to BMW for analysis.

To cut a very, very long story short, it has parameters where fresh air is introduced into the system, by design.

Don't bother debating with BMW, as it is totally normal and a limitation of the system. I'll find some of the detail and post the working parameters.

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      01-10-2011, 05:57 PM   #7
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My car under test.

Data logger installed in the passenger footwell.



Steering wheel modified with switches, to log the event.



Description from BMW data.

Quote:
Automatic Air-recirculation Control

If the AUC II sensor detects an increased level of pollutants in the environment from spark-ignition and diesel engines, the IHKA control unit will automatically switch to air recirculation mode.

To make sure there is still an adequate supply of fresh air, air recirculation is only available for a limited time:

At ambient temperatures less than 0C:
2 minute recirculated air mode -> 20 seconds fresh air mode -> 2 minute recirculated air mode -> etc.

At ambient temperatures from 0C to 6C:
3 minute recirculated air mode -> 20 seconds fresh air mode -> 3 minute recirculated air mode -> etc.

Operation without a/c function at ambient temperatures greater than 6C:
4 minute recirculated air mode -> 20 seconds fresh air mode -> 4 minute recirculated air mode -> etc.

Operation with a/c function at ambient temperatures greater than 6C:
12 minute recirculated air mode -> 20 seconds fresh air mode -> 12 minute recirculated air mode -> etc.

When the engine is started and the AUC function activated, fresh-air mode is always selected for approx. 40 seconds due to the warming phase of the AUC sensor.
Part of the above seems to conflict with the following in certain conditions.

Quote:
Condensation Sensor

The condensation sensor is controlled and powered by the roof module (FZD). Thesensor data are transferred via the K-CAN to the control and operating unit where they are evaluated. The IHKA control module receives all information sent from the FZD control module via the K-CAN spliced through the junction box.

The condensation sensor is mounted under the rain light sensor (RLS) on the mirror base.

Other names for the condensation sensor are Mist, Fogging, and Humidity sensor.

When moisture is detected by the Condensation Sensor, the following occurs:
Defroster Flaps open further
Blower speed is increased
Temperature increases
Fresh Air Flaps open 100%
Footwell Flaps are closed
Evap Temp threshold goes to minimum
It is possible to partly disable the 'total' auto function of the fogging sensor, by pressing one or more of the manual buttons on the left side of the display, (face level, etc.) some functions still continue at auto level. But it is not the total answer, as the system will still seek fresh air in some instances.

Hope this helps a bit.

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      01-10-2011, 07:24 PM   #8
shane55
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very informative pete...hope to check this when I'm back in a BM at some point in 2011
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      01-11-2011, 06:15 AM   #9
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I never posted to why I got so involved with my Climate Control system with BMW's involvement.

Basically we came from the E39 540i which had a perfectly working auto recirculation system. Did what it said on the tin. My wife is allegic to petro-chemicals so it is a key element in the car. The 330d seemed to have issues in detecting the time to shut down. The garage suspected the 'sniffer', but it didn't show up as faulty. Plus the fault was random.

Then we started getting a second issue, I could be going down the Glen and it would start pumping in more air, even over heating the car it appeared, seemed as if the CC went out of control. So the two issues were a puzzle to the garage, who to be fair, were doing their best to try and find a fault. They even changed the CC controller and all seemed fine for several weeks, then it started all over again, the random loss of control, plus the auto recirculation missing it's instructions to shut down.

Hence BMW wanting to get to the bottom of it, and the logger being fitted.

It turned out that the typical middle of the Glen issue, was likely caused by hitting different air, much higher humidity, the auto function couldn't control the anti fogging without starting the modification sequence, persistent high humidity meant it went to high level changes, so noticeable in the car, it was as if the CC was faulty.

This investigation also showed why the auto recirculation would have the random glitch as well, it too was being influenced by the other control changes, one set of commands could not be overriden by the other.

So some days, even over weeks, it would be perfect, then we'd get a weather change and it could fault over and over on virtually every trip, or over and over on the same trip.

Basically we can reach conditions where the normal parameters are pushed to the limits. My climate up here in the highlands was pushing these boundaries on the 'new' IHKA system, more than some HVAC systems.

With this knowledge we have learned to be one step ahead and either modify the system to a manual function, when absolutely neccesary and/or anticipate some heavy pollution and use the manual recirc' override.

Plus we all got a better understanding of the limitations of these latest IHKA systems.

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      01-11-2011, 09:37 AM   #10
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Thanks for sharing this Pete - this is valuable information and something I've always wanted to understand better as I've experienced similar operation with my car.

Just so I clearly understand, what are the exact settings needed to keep the outside air from coming in - does it just need to be in recirculate mode? Also, based on your information, it appears that it's impossible to run in recirculate mode constantly as based on settings and conditions, it will always allow outside air in for 20 second bursts at various pre-set intervals. Is this correct as well? It sounds like the longest you can run in recirculation mode is 12 minutes but only if you have the AC on and it's warmer than 6C.
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      01-11-2011, 10:06 AM   #11
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I second my thanks for sharing this information Pete, very very useful indeed!

I would like to echo I335's question as to whether this applies to the permanent mode (right-hand LED) which according to the manual isn't the AUC (Automatic (left-hand LED)) mode.

For example, do these intervals (listed below) for letting fresh air in apply with the right-hand LED enabled (permanent mode)?

Quote:
Automatic Air-recirculation Control

If the AUC II sensor detects an increased level of pollutants in the environment from spark-ignition and diesel engines, the IHKA control unit will automatically switch to air recirculation mode.

To make sure there is still an adequate supply of fresh air, air recirculation is only available for a limited time:

• At ambient temperatures less than 0C:
2 minute recirculated air mode -> 20 seconds fresh air mode -> 2 minute recirculated air mode -> etc.

• At ambient temperatures from 0C to 6C:
3 minute recirculated air mode -> 20 seconds fresh air mode -> 3 minute recirculated air mode -> etc.

• Operation without a/c function at ambient temperatures greater than 6C:
4 minute recirculated air mode -> 20 seconds fresh air mode -> 4 minute recirculated air mode -> etc.

• Operation with a/c function at ambient temperatures greater than 6C:
12 minute recirculated air mode -> 20 seconds fresh air mode -> 12 minute recirculated air mode -> etc.

When the engine is started and the AUC function activated, fresh-air mode is always selected for approx. 40 seconds due to the warming phase of the AUC sensor.
However it does seem a likely explanation that this applies to the permanent mode and that it lets in fresh air at regular intervals. I can see why they've done that but it should be at least explained in more detail in the manual.

Last edited by w01f; 01-11-2011 at 10:16 AM.
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      01-11-2011, 10:08 AM   #12
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Quote:
Originally Posted by F104 View Post
It's a simple two minute job to remove the filter. 6 M8 screws. There's two inlets underneath, probably for LHD/RHD cars. The inlet to the fan will be obvious. Just hit the recirculation button and you can see the valve closing. If it doesn't close you have a problem. This is also where i spray my airco cleaner into
I'm certainly interested to test this out - are there any photos or guides that show where this is located please? I may have a good knowledge of computers but have no idea about cars.
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      01-11-2011, 10:51 AM   #13
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Forgive me if some of this is coming in bits and bites, but I've put a lot of what we learned behind me and just use the car on auto with the auto recirc' button pressed and manually override when we anticipate a lung full of some dirty old car. In fact I've got in the habit of trying to get past smelly cars if we can, (we are mainly on open roads) just to keep fresh air available.

I'm sure the right hand reciculated air mode will also 'breath' when the fogging sensor dictates the car is about to mist up.

Certainly running the full auto AC, including the compressor (snowflake button illuminated) reduces the times we have issues. BUT... we have another problem locally which adds to the mix. Our typical winter period includes wide temperature swings, above and below the 'auto cutoff' (about 4-degrees) for the compressor function. This affects all AC cars. The problem with this is, the system can build up moisture, if left on and starts causing extra misting. Erratic stuff and it is better to leave the 'snowflake' off and dry out the system. So we have compound issues, if we don't think ahead and have a dry car. Obviously if we have moisture ridden cars the auto recirculation function is less reliable, due to the fogging sensing.

I do wonder if this winter is showing this up, to more users, the variable and colder temperatures. Particularly noticeable if you don't use the car every day.

Means I pick my times to use the full system, to keep it all in working order. But it is typically on auto, and snowflake button pressed when we don't expect the temperature 'drop out' we often get even mid journey.

To be honest the systems are now too complex, IMO, the older E39 CC was complex enough, but did work better in my local environment.

Prompt me for any other detail, I'll try and help. I did end up with my local BMW workshop manager (master tech) with all the technical data across the desks, trying to fathom the depths of the IHKA system. We even had the Area Technical Manager up to join the discussions when the logger was fitted. And he came up to personally discuss the outcome with us, they even looked to see if the system could be modified in any way, but that drew a blank on practical grounds.

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      01-11-2011, 10:59 AM   #14
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In winter, I use a longer mway trip to turn off the snowflake and dry out the system properly.

Other than that its just on full auto all the time.

I've noticed in the last week with temps around 3/4/5 degress their has been a marked increase in initial misting, even mist inside the dash screen and on the rear view mirror for a few minutes after start up.

A decent run with the heat on nice and warm soon sorts it out though.
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      01-11-2011, 12:57 PM   #15
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Quote:
Originally Posted by w01f View Post
I'm certainly interested to test this out - are there any photos or guides that show where this is located please? I may have a good knowledge of computers but have no idea about cars.

here's the sketch from bmwfans.info for the E92 320d. It's from a LHD drivers view (note the arrow). Open the hood and you can see covers 3, 4 and 5. You need to take no 3 off, the filter element is clipped inside of it. Two screws in the forward facing tabs, and screws on each side of the two inlets channels (the 19 positions)

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      05-19-2011, 05:26 AM   #16
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I like to drive with my system in the "Manual Recirculation" mode, as confirmed by the small right light. I turn the car off, return (doesn't matter if five minutes or five hours, etc.) to turn the car on, and the system always reverts to the position where outside air is the source. Many times I do not notice this until I get being a stinkmobile, and have to push the manual circulation button. Is this normal or should the system remember where I left it?
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      05-19-2011, 05:53 AM   #17
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Why are you using recirc mode?

You should always use OUTSIDE air to be the source, else the car will stink and get damp because of the internal air being passed round and round and no fresh clean air coming in.

That's why the car reverts to NON circulated, because that's where you want to be 99% of the time.
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      05-20-2011, 02:46 PM   #18
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I use full auto control and auto recirc all the time.

If, say, I follow a truck into the Saltash tunnel then you can hear the dampers switch to recirc to limit the intake of diesel particles. Seems to work fine to me.

I had not noticed the intermittant short opening of the fresh air inlet I just assumed it reverted to fresh air when the stinky diesel was in front no more.

What annoys me more is the constant cold air blasting from the two rearward facing vents on the top of the dash. There seems no way to stop it. I have found you can vary its temperature by changing the balance wheel 'cold/warm' near the centre dash air vents (between the DTC and lock buttons.
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      05-21-2011, 04:03 PM   #19
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Tipper - if you have the i-drive option, changes are easily and graphically made for the top / center / bottom vents. This change that I am in reference to, only adjusts the intensity of the airflow, not the temperature from each vent.
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      05-22-2011, 02:11 AM   #20
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Quote:
Originally Posted by Tipper View Post
I use full auto control and auto recirc all the time.

If, say, I follow a truck into the Saltash tunnel then you can hear the dampers switch to recirc to limit the intake of diesel particles. Seems to work fine to me.

I had not noticed the intermittant short opening of the fresh air inlet I just assumed it reverted to fresh air when the stinky diesel was in front no more.

What annoys me more is the constant cold air blasting from the two rearward facing vents on the top of the dash. There seems no way to stop it. I have found you can vary its temperature by changing the balance wheel 'cold/warm' near the centre dash air vents (between the DTC and lock buttons.
This is how I run mine all the time and it works fine for me too but dash vents do blast out bloody cold air but I run with them directed down the way
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      05-22-2011, 05:28 AM   #21
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No not the face level adjustable vents, the two that are set into the top of the dash about half way back from the windscreen.

Even rear seat pasengers complain about them!

And no idrive I'm afraid...I've got the privately purchased cheapo SE version not a company car! But it has got Bi-Xenons and Angel eyes that many seem to lust after.
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      05-22-2011, 06:44 AM   #22
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Is this AUC recirc control an optional extra or is standard on all cars with climate control?
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