G21 3-series rear temperature control

[Prawo Jazdy]

Hello,

I’ve had an M340i for a few months. It sends hot air out of the rear vent and rear footwells regardless of anything I do. Max A/C doesn’t stop it, turning off the rear vents or controls on the iDrive doesn’t stop it, the physical rear vent controls don’t stop it.

Although referenced, there doesn’t seem to be a definite reason online for this. Has anyone had this and solved it? We’re driving to Switzerland in the summer, and we will be taking a different car if this keeps up!

[Wills2]

I'd ask/search on bimmerpost, thread below on the same issue but on an X5. (the good thing about the Americans is that they get every kind and type of failure and post about it)

https://g05.bimmerpost.com/forums/showthread.php?t...

[Gassmi]

Had this exact thing on a G21. It’s a stuck blend flap motor for the rear heater core. Common fault. Dealer fix under warranty. Temp fix is to set rear temp to LOW and fan speed to zero in iDrive then cycle ignition. But get the flap motor replaced before Switzerland.

[Prawo Jazdy]

Urgh. No longer under manufacturer warranty. I’ve got one of those warranties a non-BMW dealer gives you which probably only covers me for an engine inexplicably exploding. I’ll have to have a look.

Thanks for the replies.

[Prawo Jazdy]

This video does not describe the issue I have, but I wanted to eliminate things that I could check myself. It's an X3 rather than a 3-series, but that part seems to have the same flaps layout.

https://www.youtube.com/watch?v=_Mv9PlNZtj0&pp...

The large flap which is the subject of this video is in the 'correct' place when I remove the filter. However, when I lock/unlock the car, wake up the electronics so that the ventilation starts, and select recirculate, nothing about the flap positions changes at any of these stages. Have I misunderstood, or is that not correct. I don't really think airflow is an issue, so this is all probably a red herring. However, there is so much talk on Bimmerpost about cabin filters causing this issue, that I thought it was worth investigating.