[alkin2222]

Hi,

I`ve got a 328 i GT 2015.

Since 1 year ago, after I took the care for periodical checkups, something weird happened: (none of the BMW local offices and repair shops here could figure that out)

whenever the outside temp goes below 20 degrees centigrade, I have no control over M - A button and the polluted air from outside comes inside the cabin. This never happens during summer or where ever the temp is above 20 degrees.

The thing is, far as I know, M stands for manual so whenever the vent system is on M, no air should come inside the cabin and whenever it is on A it lets the air flows in and the moment it detects any pollution it should close the vent.

The assumption above was a fact actually for the first few months and no matter what the outside temps were, whenever it was on M, vents were always closed and nothing would come inside the cabin.

Help me out.

[Billfitz]

Unless you use the recirculate mode (see your manual) the outside air always enters, that's why it has a cabin air filter. You should only use recirculate when you have to, otherwise moisture will build up in the car, even in the desert, as your breath is a moisture source.

[alkin2222]

Appreciate the response.

I remember whenever I set it on M, it always stayed on M and even if it jumps to A, it should automatically detect the polluted air and stop it from coming inside, am I right?

What do you think is the problem here? what filter or part should bee looked into or changed?

[Billfitz]

Originally Posted by alkin2222

it should automatically detect the polluted air and stop it from coming inside, am I right?

I don't know how it would do that. Mine has never jumped from A to M or from M to A by itself, only when I've done something to cause it.

[alkin2222]

Aha, by "the recirculate mode" you meant putting it on M ?

[Billfitz]

There is a specific recirculate button. It's in the manual.