air-con circulation - Permenant - DIY - E90

Aaron_BMW

Well-Known Member
Dear Guys,
Just for sharing how I managed to block the inlet hole to the air-con circulation vent.

Problems:
1. Our BMW air-con circulation button needs to be pressed to switch on each time u start ur car.
2. I sometime smell exhaust fumes while driving even if the air-con circulation for internal circulation is switch on.

Solution:
Using a sponge to block the inlet hole. No matter if the air-con circulation is on or off, the external air is block all the time. Please see pics for a better understanding.

IMG_8204_zps5f501563.jpg

The above pic shows the air-con circulation vents which is electronically controlled.

IMG_8205_zps64586e73.jpg

This is a closed up shot of how the vents look like.

IMG_8206_zps8a8b9e64.jpg


IMG_8207_zps22a2dcc1.jpg


So by doing this, I managed to block external air from going into the cabin.
All u need is a sponge and remove 5 screws. 10 min job.

Hope this is useful for u.
Cheers~!

 
Re: air-con circulation - Permenant - DIY - E90

Hi Aaron,

You should try turning on ur A/C with the circulation button instead of the + Fan button. That way the A/C switches on with the previous setting. No need for the sponge.
 
Re: air-con circulation - Permenant - DIY - E90

I do.
Sometimes still have exhaust fumes from outside.
So that's why I use the sponge
 
Re: air-con circulation - Permenant - DIY - E90

Just curious, what's the difference between pressing the air circulation button to allow external air to come in bit by bit, versus opening the window. The latter allows air to come in faster le.
 
Re: air-con circulation - Permenant - DIY - E90

C3P0 said:
Just curious, what's the difference between pressing the air circulation button to allow external air to come in bit by bit, versus opening the window. The latter allows air to come in faster le.

The difference is - THE WEATHER, when it RAINS.
 
Re: air-con circulation - Permenant - DIY - E90

frankly speaking I wont do this my ride.
is good to have some fresh air in occasionally especially on long journey
We need some fresh AIR during the long trip otherwise we are only breathing our own circulated air.
If 1 had block the opening , maybe you can consider open your window every 1 hour for few seconds
Do remember our weather and engine heat could cause the sponge dry and become like powders later still follow Air into cabin
 
Re: air-con circulation - Permenant - DIY - E90

kenntona;1028860 said:
The difference is - THE WEATHER, when it RAINS.
Thumbs up for a mature and quality reply. I forgot about that. And probably in other countries - when it snows.
 
Re: air-con circulation - Permenant - DIY - E90

Hey bro Aaron_BMW, looks like you been to Dr Francis workshop again. Thumbs up on this DIY fix! But i probably won't do this though, used to pressing the air-recirculating button already every time i start the car :)
 
Re: air-con circulation - Permenant - DIY - E90

there must be a reason why BMW made it that way....
but i just dont know why....
better dont block it.....
 
Re: air-con circulation - Permenant - DIY - E90

Thank you for generously sharing !!
my electric motor spoilt actually and i had been putting up with this shi7 for a week already.
no time to go fix it
 
Re: air-con circulation - Permenant - DIY - E90

eokh;1028954 said:
Thank you for generously sharing !!
my electric motor spoilt actually and i had been putting up with this shi7 for a week already.
no time to go fix it


Ok, maybe my solution works for u.
 
Re: air-con circulation - Permenant - DIY - E90

roberttan;1028868 said:
frankly speaking I wont do this my ride.
is good to have some fresh air in occasionally especially on long journey
We need some fresh AIR during the long trip otherwise we are only breathing our own circulated air.
If 1 had block the opening , maybe you can consider open your window every 1 hour for few seconds
Do remember our weather and engine heat could cause the sponge dry and become like powders later still follow Air into cabin


Thanks for the tip.
I will do that on long distance trip.
 
Re: air-con circulation - Permenant - DIY - E90

Guys,
I think this simple modification should be quite harmless.

Most Japanese cars have the circulation easily switch to permenent also.
 
Re: air-con circulation - Permenant - DIY - E90

Found this with a search, from BMW themselves: http://prodcds.bmwuniversity.com/library/bmw/Technician/Core%20Courses/ST054%20Climate%20Control/06%20Climate%20Control%20Systems%20and%20Functions.qxp.pdf
It illustrates why despite us forcing the re-circulation to happen by pressing the button, the software can over-ride it in certain situations.

Air-recirculation Mode
In air-recirculation mode, the flow of outside air can be stopped to prevent pollution from entering the vehicle, e.g. in traffic congestion. Air inside the vehicle is continually re-circu- lated.
To make sure that there is a sufficient supply of fresh air, air-recirculation mode is only available for a limited time. (30 minutes air recirculation -> 30 seconds partial fresh air -> 30 minutes air recirculation -> etc.)


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:

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

When the engine is started and the AUC function activated, fresh-air mode is always selected for approximately 40 seconds due to the warming phase of the AUC sensor.

Condensation Sensor Program
The IHKA control unit evaluates the condensation sensor signal (humidity). If condensa- tion on the windscreen is imminent, the following measures are initiated in sequence to prevent condensation from forming:
• Open defrost flaps further.
Switch from air-recirculation/AUC/automaticair-recirculation mode to partial fresh-air mode.
Switch from partially fresh airinair-recirculation/AUC/automatic air-recirculation mode to fresh air.
• Increase blower air volume.
• Reduce air volume for the footwell.
• Increase desired temperature value.
 
Re: air-con circulation - Permenant - DIY - E90

Great info!! Thanks
 
Re: air-con circulation - Permenant - DIY - E90

Could have been coded to go into auto everytime in minutes.......
 
Re: air-con circulation - Permenant - DIY - E90

Ever thought of putting a packet of aquarium charcoal bits there ? You will need to wash it thoroughly though. Now you have an active carbon filter :) They cost very little.
You can literally smell the difference in air quality when the vent is opened.
Down side is you need to replace it once in a while
 
Re: air-con circulation - Permenant - DIY - E90

i coded my manual aircon to be set to circulate as default...
 
Re: air-con circulation - Permenant - DIY - E90

lim_ck;1029972 said:
i coded my manual aircon to be set to circulate as default...

Thanks for sharing.
I think this info helps many
 
Re: air-con circulation - Permenant - DIY - E90

i tried to get one workshop to code for me. But the setting cannot be 'stored' was told that the ECU have problem with that coding......
I also read that older E90 05-06 production the coding for circulation dun work. Or wrong?

Pls share.

thank you.,
 

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