Cabin Filters

rirrgang · 09-08-2019, 09:34 AM

Good morning all. I replaced the two cabin filters yesterday, I do that every year. I am curious as to why there are two filters. I see the how the lower one works but for the life of me I can't figure out what to top one does.
Thanks

Barbera335 · 09-08-2019, 10:30 AM

The pair under the hood filter fresh air from the outside and the one in the glovebox filters the reciculated air in the interior of the car. I just did both of mine a few months ago.

rirrgang · 09-09-2019, 08:23 AM

Yes, I get that. I have replaced the one in the glove box as well but I still don't understand what air flow the top filter is flowing on the under the hood pair. The bottom one is clear enough

Barbera335 · 09-09-2019, 11:52 AM

It flows, there is an air gap between the lid and the filter. It must be flowing equally to the bottom as both the top and the bottom always look equally dirty when I change them.

rirrgang · 09-10-2019, 10:35 AM

I have the arrow on both filters facing up as the directions on the box said to do. I'll flip the top one over if that's the case.
Thanks for the reply

tracer bullet · 09-10-2019, 01:59 PM

Any chance you remember which sides were dirty when you took them out? The clean sides would be the direction the air flows towards and the direction for the arrows to point. I think Barbera335 is right about them pointing towards each other and how the flow goes.

Opie55 · 09-11-2019, 09:04 PM

I agree it's a goofy design. Basically you have a vertical hole in the firewall through which your blower motor is sucking air. Rather than having a single vertical filter covering that hole, or an "elbow" housing that is closed on the top or bottom to allow for the use of a single filter, BMW made an open housing that allows air in at the top or bottom. The bottom is wide open. The top seems closed because of that cover over the filters, but it's not really. It's a very loose fitting cover that allows a lot of air in. That top cover is really to divert rain over the filters, not to keep air out.

WagonR · 09-25-2019, 12:26 AM

To follow up with this - has anyone replaced the cabin filters that are above the glove box? At first I thought there were just the filters in the engine bay, by the firewall, but then I saw this:

https://www.youtube.com/watch?v=uyXqacQ1z1w

and this:

https://www.carcarekiosk.com/video/2..._cabin/replace

It looks like this filter is also part of the change?

BMW part number 64119237159

https://www.amazon.com/Genuine-BMW-C.../dp/B01JEG1HGG

Is this something everyone is doing? I missed it and assumed the engine bay filter was the only one.

Opie55 · 09-26-2019, 09:53 PM

Quote:

Originally Posted by WagonR

To follow up with this - has anyone replaced the cabin filters that are above the glove box? At first I thought there were just the filters in the engine bay, by the firewall, but then I saw this:

https://www.youtube.com/watch?v=uyXqacQ1z1w

and this:

https://www.carcarekiosk.com/video/2..._cabin/replace

It looks like this filter is also part of the change?

BMW part number 64119237159

https://www.amazon.com/Genuine-BMW-C.../dp/B01JEG1HGG

Is this something everyone is doing? I missed it and assumed the engine bay filter was the only one.

Yes, you should change those. I just did mine and they were pretty dirty.

WagonR · 09-27-2019, 10:08 PM

Quote:

Originally Posted by Opie55

Yes, you should change those. I just did mine and they were pretty dirty.

Seems like they may be even more important than the filter by the cowl. I haven't seen much on changing the ones above the glovebox. I just replaced both sets of filters, and the ones in the cabin were worse.

Just a PSA to think about both...

OldenburgerM3 · 05-02-2020, 02:42 PM

FWIW: I locally sourced the filters this week since I didn't want to spend $10 on shipping a dumb filter. I ended up with:
STP Cabin Air Filter CAF90125P for the engine-bay cabin air and
MicroGard 4106 for the glove-box cabin air location.

09-08-2019, 09:34 AM	#1
rirrgang New Member 4 Rep 29 Posts Drives: 2012 X3 x35i Join Date: Oct 2018 Location: San Jose, Ca. iTrader: (0)	Cabin Filters Good morning all. I replaced the two cabin filters yesterday, I do that every year. I am curious as to why there are two filters. I see the how the lower one works but for the life of me I can't figure out what to top one does. Thanks
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09-08-2019, 10:30 AM	#2
Barbera335 Captain 169 Rep 660 Posts Drives: F25 Join Date: Jul 2008 Location: socal iTrader: (0)	The pair under the hood filter fresh air from the outside and the one in the glovebox filters the reciculated air in the interior of the car. I just did both of mine a few months ago.
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09-09-2019, 08:23 AM	#3
rirrgang New Member 4 Rep 29 Posts Drives: 2012 X3 x35i Join Date: Oct 2018 Location: San Jose, Ca. iTrader: (0)	Yes, I get that. I have replaced the one in the glove box as well but I still don't understand what air flow the top filter is flowing on the under the hood pair. The bottom one is clear enough
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09-09-2019, 11:52 AM	#4
Barbera335 Captain 169 Rep 660 Posts Drives: F25 Join Date: Jul 2008 Location: socal iTrader: (0)	It flows, there is an air gap between the lid and the filter. It must be flowing equally to the bottom as both the top and the bottom always look equally dirty when I change them.
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09-10-2019, 10:35 AM	#5
rirrgang New Member 4 Rep 29 Posts Drives: 2012 X3 x35i Join Date: Oct 2018 Location: San Jose, Ca. iTrader: (0)	I have the arrow on both filters facing up as the directions on the box said to do. I'll flip the top one over if that's the case. Thanks for the reply
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09-10-2019, 01:59 PM	#6
tracer bullet Brigadier General 2388 Rep 3,530 Posts Drives: '11 135i , '15 X3 35i Join Date: May 2011 Location: Saint Paul, MN iTrader: (1)	Any chance you remember which sides were dirty when you took them out? The clean sides would be the direction the air flows towards and the direction for the arrows to point. I think Barbera335 is right about them pointing towards each other and how the flow goes.
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09-11-2019, 09:04 PM	#7
Opie55 Colonel 1190 Rep 2,904 Posts Drives: '15 650i Convertible Join Date: Apr 2018 Location: US iTrader: (0)	I agree it's a goofy design. Basically you have a vertical hole in the firewall through which your blower motor is sucking air. Rather than having a single vertical filter covering that hole, or an "elbow" housing that is closed on the top or bottom to allow for the use of a single filter, BMW made an open housing that allows air in at the top or bottom. The bottom is wide open. The top seems closed because of that cover over the filters, but it's not really. It's a very loose fitting cover that allows a lot of air in. That top cover is really to divert rain over the filters, not to keep air out.
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09-25-2019, 12:26 AM	#8
WagonR First Lieutenant 293 Rep 360 Posts Drives: 2017 M2 Join Date: Jun 2016 Location: Portland, OR iTrader: (9)	To follow up with this - has anyone replaced the cabin filters that are above the glove box? At first I thought there were just the filters in the engine bay, by the firewall, but then I saw this: https://www.youtube.com/watch?v=uyXqacQ1z1w and this: https://www.carcarekiosk.com/video/2..._cabin/replace It looks like this filter is also part of the change? BMW part number 64119237159 https://www.amazon.com/Genuine-BMW-C.../dp/B01JEG1HGG Is this something everyone is doing? I missed it and assumed the engine bay filter was the only one. __________________ Current: 2017 F87 M2 6MT 2013 F25 X3 3.5i 2008 E90 M3 6MT
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05-02-2020, 02:42 PM	#11
OldenburgerM3 Private First Class 72 Rep 183 Posts Drives: 2011 Jet Black M3 Coupe Join Date: Feb 2011 Location: TX iTrader: (0)	FWIW: I locally sourced the filters this week since I didn't want to spend $10 on shipping a dumb filter. I ended up with: STP Cabin Air Filter CAF90125P for the engine-bay cabin air and MicroGard 4106 for the glove-box cabin air location.
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