BMW M2 AC System Failure: Temperature Sensor Suspect

Hi there! I had a similar issue with my 2015 BMW M4 last summer. The symptoms were exactly like yours, AC controls dead, error messages, the whole thing. After trying basic troubleshooting, I took it to my trusted workshop. Turns out the AC control unit itself was faulty and needed replacement. The repair cost me around 980 Euro, but it fixed the problem completely. Before I share more details, could you tell me if you're getting any specific error codes? Also, have you noticed any other electrical issues? This could help determine if it's isolated to just the AC system. BTW, my cousin has a 2017 BMW M3 and faced similar issues. These control units can be a weak point in these models. Let me know the details and I'll try to help further!

Thanks for your detailed response! My M2 just hit 139014 KM and had its latest service two weeks ago. Actually, after reading your reply, I checked and I'm getting error code 8D-31 on the iDrive system. No other electrical issues so far, everything else works perfectly fine. My AC just suddenly stopped working during a drive yesterday. I was hoping it wouldn't be the control unit since that's quite expensive to replace. I'll probably take it to the shop tomorrow to get it properly diagnosed. Really appreciate you sharing your experience with the M4, at least now I have some idea what I might be dealing with. Did your cousin's M3 also need a complete control unit replacement, or was it something else?

Hey again! Thanks for providing those details about your M2. Yeah, that error code 8D-31 is exactly what I got on my M4 before the whole AC system went dead. At first, I was hoping it wasn't the control unit either, I totally get wanting to avoid that expense! Interestingly, my cousin's M3 turned out to be a different issue, he got lucky. His problem was just a blown fuse and some corroded connections that they cleaned up. Much cheaper fix, around 150 Euro or so. But these control unit failures are pretty common in our generation of BMWs, especially once they hit around 120,000-150,000 KM. Since you mentioned having the service done two weeks ago, maybe check with them if they noticed anything unusual during the service? Sometimes these units start showing subtle signs before completely failing. In my case, I remember the AC fan speeds being a bit inconsistent for about a month before everything stopped working. I'd definitely get it checked out soon though. When mine failed, I waited a couple of weeks hoping it would somehow fix itself (spoiler alert: it didn't), and ended up driving without AC in peak summer. Not fun at all! Keep me posted on what your mechanic says, hopefully you'll get a cheaper fix than I did.

Thanks so much for all this info! You're right about getting it checked soon, I just booked an appointment with my mechanic for tomorrow morning. I actually called the service center about my recent visit, but they said they didn't notice anything unusual with the AC during the routine check. What really worries me is that my symptoms match exactly what you experienced with your M4. Same error code and everything. At least my car's been consistently maintained, so hopefully that counts for something. I'm mentally preparing myself for that control unit replacement cost, but still keeping my fingers crossed it might be something simpler like your cousin's M3 issue. I'll update you once I get the diagnosis. I definitely don't want to end up driving without AC, the weather's getting warmer and that would be pretty miserable. Thanks again for sharing all your experience. It's really helpful knowing what to expect when I take it in tomorrow!