A vs M in Climate Control

[Arm]

I was reading up on the difference between modes on the climate control system and wanted to know what people's thoughts are between setting the recirculation modes....A, M, or no light on at all.

A mode, if illuminated, is supposed to detect external pollutants and automatically close off external air.

M mode, if illuminated, shuts off all outside air and is full recirculation mode until a sensor supposedly detects moisture that can cause fogging and turn A mode back on again.

Both lights off means full outside air at all times.

I've my suspicions that A mode just doesn't work because unless I have the mode set to M, I always detect and smell external odors be it exhaust fumes, smells from passing a restaurant, etc. So I'm not sure if there even is a sensor that detects external pollutants and such things.

Any thoughts?

 

[eNate]

It's fairly easy to detect particulate above a certain size, but not odors. So that's my guess -- the car isn't "seeing" anything of concern, e.g. diesel particulate, dust, pollen.

I haven't changed my cabin air filter yet so I don't know if the i3 has a charcoal filter for odor filtration in addition to a particulate (HEPA type) filter.

 

[Arm]

How often are you supposed to change it? The good ones seem quite expensive.

With the fires we had out here lately in So Cal, I'm tempted to do so even though I've had the car for less than a year.

 

[eNate]

According to the BMW maintenance guide, "Replace ventilation microfilter every 2 years based on the vehicle production date, or in connection with scheduled vehicle check."

But I've seen suggestions for 5,000 miles, 30,000 miles, and annually. With the pervasive wildfire smoke, I'd agree that changing it (or at least checking it) later this fall is a good idea.

 

[Deutsch100]

Living in So. California with wildfires and smog....I too think the filter should be changed more regularly, just like we do in our homes. Is there an easy way to get to the filter, w/o taking the car or dash apart? Thanks.

 

[eNate]

... Is there an easy way to get to the filter, ...

I haven't changed mine yet, but YouTube is your friend.

https://youtu.be/0LNnvu3ibIo

 

[Deutsch100]

Thanks eNate. Not too hard!

 

[Arm]

The OEM ones are Denso and are super expensive...$80 at the dealer.

 

[trumpetdoug]

Is there a recommended place to purchase these filters outside a dealer? Might be up for doing this job myself.


Doug - out

 

[eNate]

These are the ones I purchased. I won't vouch for them yet, but they're the same as Mini so there's a larger group of users out there than just us.

https://www.amazon.com/gp/product/B076C1HG1P

 

[Arm]

Are these covered under the standard bmw maintenance plan? For the first two years or something like that?

 

[jadnashuanh]

They used to be...BMW has changed the coverage, depending on the MY, so you'd have to ask, or it would be covered in the warranty documents but those can be harder to decipher sometimes.

 

[gt1]

They replaced mine under the included mainenance early this week.

 

[alohart]

They replaced mine under the included mainenance early this week.

This must be a dealer choice in the U.S. During the first scheduled maintenance of our 2014 BEV in November, 2016, our dealer replaced the filters. During the final scheduled maintenance in November, 2018, our dealer informed me that filter replacement was no longer being performed routinely.

 

[jadnashuanh]

Originally from what I remember, cabin filter change recommendations were time based, but now are distance. That may be reasonable, but can be problematic in some situations like say you drive lots of dirt roads, or often get some really polluted air whether from pollen, smoke, diesel fumes, or dust.

They're kind of a pain to take out to just look at their condition. Laborwise, just as cheap to put new ones in, but maybe not if you're doing it yourself.

 

[eNate]

With all the electronics in our cars, a simple post-filter differential pressure sensor would be an easy add to indicate when airflow is sufficiently impeded. Yeah, another doodad to malfunction!

 

[MagicCarpet]

I wonder if mine is not closing the outside air vents fully in M.
Most of my trips are short and I always have M selected but still get diesel fumes and smoke entering the system from time to time. I cycle the controls Auto to Manual it doesnt fix.
This seems to be happening only in the last 6 months so might be a jammed servo. If I ever replace the filter I'll try to look at the mechanism then, its on my to-do list

 

[Arm]

I did a little digging and apparently the filters are part of the BMW Care Package for cars 2017 and newer. That coverage of course is 3 years/36000 miles.