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Discussion Starter · #1 ·
Did a search but did not find a definitive answer to my question -

Fair warning - might be a dumb question!

When you get the microfilter service/replacement done (see attached invoice), three filter elements are replaced - two filter elements are accessed from under the hood, passenger side - these two filter elements filter the air coming from the outside into the cabin - correct?

A third filter element is installed inside the cabin, below the glove compartment/front passenger footwell. This is the activated charcoal filter that filters cabin air when the setting is set to recirculate.

This filter inside the cabin also gets activated when the LED light on the A button is lit AND the sniffer detects some fumes that are charcoal filter sensitive - correct?

Is this inside cabin filter element the activated charcoal filter OR is it another device/filter that does not get replaced during this microfilter service?

How often should these filters be replaced - once a year? Replace all three elements at the same time OR are the two filter elements inside the hood replaced more often than the one inside the cabin?

Finally, are there any resets done during this microfilter service (like you do for any engine oil or transfer case oil replacement)?

Thanks
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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No resets. Recirc is automatic when the left LED is lit. The cabin recirc filter may be charcoal, the two sections of the external filter should be charcoal. I will probably do the cabin air filters annually. The physical chemistry required to detect exhaustion of an activated carbon filter is mind boggling. The test to detect clogging of a filter is too sensitive to be inexpensive.

My greatest career success was replacing a radioactive coolant water polishing dual-filter assembly of zeolite resin and activated charcoal under budgeted dollars, hours and man-REM.

A common tool was a HEPA filtered vacuum cleaner that had to be certified tested effective with a standard particulate test medium and less than 1" H2O differential pressure.
 

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Discussion Starter · #3 ·
Thanks for the response.

Just looked up my service history (I used to have the maintenance plan, expired at 100K miles) . . . cabin filters (all three filter elements) along with air intake filter (silencer) got replaced approximately every 30,000 miles (18 to 24 months) . . .

Going forward I will change it about every two years - match it up with the nearest engine oil change indicated by iDrive/CID . . . for me that is around 10,000 miles.
 

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Did a search but did not find a definitive answer to my question -

Fair warning - might be a dumb question!

Q-1. When you get the microfilter service/replacement done (see attached invoice), three filter elements are replaced - two filter elements are accessed from under the hood, passenger side - these two filter elements filter the air coming from the outside into the cabin - correct?
A-1: yes​
Q-2. A third filter element is installed inside the cabin, below the glove compartment/front passenger footwell. This is the activated charcoal filter that filters cabin air when the setting is set to recirculate.
A-2: no, this filter is not charcoal activated...but yes, it does filter recirculated air within the cabin​
Q-3. This filter inside the cabin also gets activated when the LED light on the A button is lit AND the sniffer detects some fumes that are charcoal filter sensitive - correct?
A-3: yes, this filter is put into service...but it's because the AUC sensor has activated the HVAC system's recirculation mode. It's the recirculation mode that brings the filter into play...not because "the sniffer" detected fumes. Your "cause" and "effect" is slightly misplaced. In a round-about way the sniffer is the cause that brings the effect...but the actual cause is that recirculation mode is forced into action...which brings in the use of the recirculation filter.​

Q-4. Is this inside cabin filter element the activated charcoal filter OR is it another device/filter that does not get replaced during this microfilter service?
A-4: the "inside" recirc filter isn't necessarily an "activated charcoal" filter unless you specifically purchase one (usually aftermarket). It's the filters used in the engine bay that are "activated" (based on the part nbrs you gave in the PDF).​
Q-5. How often should these filters be replaced - once a year? Replace all three elements at the same time OR are the two filter elements inside the hood replaced more often than the one inside the cabin?
A-5: I would say that the conditions that you drive in determine how often the filters should be changed. If you live/drive in dusty conditions (dirt/gravel/unpaved roads/etc) or live in an area where pollen can be extreme certain times of the year (like how pollen can cover vehicles in the spring in areas like Atlanta GA)...then you may want to change your filters (or at least check them) frequently to see how clogged they are.​

Thanks
See replies in bolded text above. :)

Also, in diagram below and link to part nbr index...item #1 is the charcoal filter(s) installed in the engine bay which can be "activated" or non-activated (your receipt says they are the activated type and you received two filters...one for the left side and one for the right side). And item #2 is the interior recirculation filter:

 

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Discussion Starter · #5 ·
Thanks QSilver7 for the very detailed response, sure appreciate it!

Didn't know outside air got separated into driver and passenger side streams at the filter point itself . . . I thought it happened further downstream and the two filter elements was mainly for manufacturing convenience.

My no-knowledge SA said there is a charcoal canister by the recirculation filter inside the cabin and it also gets replaced as part of the air filter service. I don't think he is correct . . . the charcoal canister I thought was part of the fuel tanks system.

Follow up question - please confirm for air filter maintenance/service only the above mentioned three filter elements need to be replaced, nothing more - correct?

Thanks.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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The cabin recirculation filter located in the passenger footwell MAY be charcoal, and MAY be the same dimensions as the external inlet filters.
 

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Also, in diagram below and link to part nbr index...item #1 is the charcoal filter(s) installed in the engine bay which can be "activated" or non-activated ]
My dealer charged me an extra $120 for programming to activate my filters.

.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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My dealer charged me an extra $120 for programming to activate my filters.
That's only reasonable, as he had to buy/build the heated nitrogen stream ovens. Of course he should expand and service the larger technical community.
 

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Thanks QSilver7 for the very detailed response, sure appreciate it!

Didn't know outside air got separated into driver and passenger side streams at the filter point itself ...
It does not. It would require separate blowers for each stream, wouldn't it?

Re activating filters for $$ - lol; activated = 'charcoal', non-activated - paper.
 

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explaining a joke ruins it. ;)
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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Re activating filters for $$ - lol; activated = 'charcoal', non-activated - paper.
In re activating filters, charcoal is activated by baking in a reducing atmosphere, usually oxygen, and may be re-activated, by baking it in an inert atmosphere, usually nitrogen at 250°C. Charcoal filter has not necessarily been activated.

A gram of charcoal filter has 3,000 m^2 area (!) for absorption. Density is typically 0.5 gram/cubic centimeter, that is loosely packed as in a filter. Submarines use it by the 25# sack to change the charcoal filters. The best loved of which are fart-gobblers in each head stall. The odd numbered sanitary tanks are blown overboard by air pressure and the excess volume is vented back inboard to conserve 'breathing' air - through charcoal filters.

The first breaths of fresh air after months at sea and submerged taste like a cut copper penny. Only FMB boomers tours are 90 - 100 days. My longest 'tour' was fourteen months for the Yom Kippur War, 100 days on station relieved by 24 hours with a tender to replenish food and lube oil, then back on station boxing the box.
 

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...100 days on station relieved by 24 hours with a tender to replenish food and lube oil, then back on station boxing the box.
OMG...the locker room jokes rattlin' around in my head :rofl::rofl::rofl: ...they could write themselves...lube oil...submarines...90-100 days submerged ...:bustingup:bustingup:bustingup
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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OMG...the locker room jokes rattlin' around in my head...they could write themselves...lube oil...submarines...90-100 days submerged ...
After the nuclear submarine program became mature, psychological testing ostensibly ended but there were never the problems that you allude.

I deleted a sea story.

This was Zumwalt's Navy. I doubt such shenanigans go on now-a-days. I would not be in today's Navy. The next American submarine to sink will have females aboard.
 

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All joking aside...those that serve...and especially those that do so in the capacity that calls for the mental/psychological certitude to do duty in a sub...have my utmost admiration and gratitude. :)
 
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