9C4A – stepper motor dynamic pressure

[HellRazor35]

Thanks for the update... I understand that there are a lot of false positives with bimmer codes...reason I am really leaning towards replacing the part is that when I try and activate the motor I can hear it and it keeps cycling like its trying to move....unlike the other flap motors.

When I activate them to 50% via the BimmerGeeks ProTool that activate then shut down and a noticeable change happens in the vents and air flow..


What exactly does the the Dynamic-pressure-flap motor control?

The other day I check the cabin filter to confirm it was clean and clear and could see the motor and its not hard to get to....

I am also thinking that I might have a Blower motor resistor going...
No codes for it though

Ill update once parts replaced

[Toothbrush]

Well, there's an easy way to tell if the stepper motor is doing it's job, or perhaps there's something blocking the flap itself. Simply

1. Remove the passenger side partition cover - 13 mm socket for plastic sockets - quarter turn only!! (just a simple lever that 'locks' the cover in place by swinging 45 degrees, doesn't screw on
2. Disconnect the fresh air sensor - connector has a little lever to push in
3. Remove the fresh air filter cover - held on the same way as the partition cover above)
4. Switch the A/C from outside air to inside air and back, you should see the flap/door open and close

You may find a blockage or evidence of water intrusion (bad). If the door doesn't move like in the attached video, there's probably something wrong with that stepper motor. If it does move...

You can see mine opening in the attached video. The white part behind the door is the blower motor fan spinning.

[HellRazor35]

Thanks for taking the time and getting the video...Big Help!
So do confirm that is the flap that the dynamic pressure motor controls then?

Ill confirm that this weekend

[Toothbrush]

Originally Posted by HellRazor35

Thanks for taking the time and getting the video...Big Help!
So do confirm that is the flap that the dynamic pressure motor controls then?

Ill confirm that this weekend

Hmm, well examining it a bit more, looks like I was incorrect. The dynamic stepper pressure motor must activate a different flap. I was looking in ISTA and saw there was fresh air stepper motor listed separate from the dynamic pressure stepper motor. Examined the system a bit more and, well see images. Still not a bad idea to make sure that one I mentioned above is working.

Edit: I'm guessing that honey comb looking section is the flap you can see in the video I posted, but not sure how the dynamic stepper motor interacts with it, if at all now. There's not any clear documentation on what that particular motor actually does.

[HellRazor35]

Perfect, I still need to get ISTA working in the laptop. I can get it installed but will not talk to the ECU for some reason. I am guessing that I have a connection setting off some where.

Dont know if you have ever use the BimmerGeeks PROTOOLS on the Android but its pretty good. But ISTA in this situation would be choice.

Thanks for the PICs and confirming....Ill keep updating.

Its pretty cold here just dumped 5-6inch snow today and suppose to get down in the low low 20's tonight..
just make working on this a lot less fun

FYI Pretty sure that flap is working because when I activate it in ProTool the air flow changes...I'll try capturing some video when I do this

[Toothbrush]

I tested out BimmerGeeks app when they first released it and it looked promising but haven't used it since then. I have Carly (from before they were a subscription thankfully), INPA, ISTA and OBD Fusion for quick and dirty live data while driving.