BMW Z4 Defrost Flap Problems: Fix Guide & Symptoms

I've got some experience working on BMWs (moderate expertise level). Had a similar issue with my 2001 BMW 3 Series, and my friend owns a Z3 that went through the same thing. The defrost flap problem is pretty common in these models. Mine was acting up just like yours, foggy windows, weak heating, and those annoying error messages. Took it to my regular workshop, and they found that the cables and electrical connections to the flap motor were corroded and loose. The fix wasn't too complicated, they replaced the connections and recalibrated the system. Cost me about 95 Euro, and it's been working perfectly since then. Before I can give more specific advice, could you share: Are you hearing any clicking sounds when switching between climate modes? Have you checked if the air is still coming through other vents when this happens? What exact error message are you getting on the display?

Thanks for sharing that info! I'm dealing with similar symptoms with my Z4 at 26173 KM since the last service. Actually, I do hear this weird clicking noise when switching between modes. The air barely comes through any vents when the defrost is selected, and I get an "LA FAULT" message on the climate display. Been super annoying lately, especially with all the window fogging. Good to know about those corroded connections, that definitely sounds like it could be my issue. Might save me some troubleshooting time at the workshop.

Hey again! Yeah, that "LA FAULT" message and the clicking sound you mentioned are exactly what I experienced with my Z4 too. When you said it's happening at 26173 KM since the last service, it's pretty much spot on with when mine started acting up. The clicking noise is a dead giveaway, it's definitely that defrost flap mechanism. In my case, after they fixed those corroded connections I mentioned before, they actually found the flap motor itself was on its way out too. Apparently, moisture had gotten in there over time and messed things up. The mechanic showed me the old part, and you could see the corrosion build-up. One thing I forgot to mention in my last reply, after they replaced both the connections and the motor, they also treated the area with some moisture-resistant coating to prevent it from happening again. It's been about a year now, and I haven't had any issues since. Since you're getting the same symptoms I had, especially that weak airflow when using defrost, I'd bet you're looking at a similar fix. Just make sure whoever works on it checks both the connections and the motor itself. Would hate for you to replace one thing only to find out you need the other part too.

Thanks so much for the detailed follow-up! That's super helpful to know about both the connections and the motor potentially being the culprits. I'll definitely mention this to my mechanic when I take it in. The moisture-resistant coating sounds like a smart preventive measure too, I'll ask about that as well. Really appreciate you taking the time to share your experience. It's giving me a much better idea of what to expect with the repair. Will probably book it in next week to get this sorted before it gets any worse. Thanks again for all the advice!