BMW 3 Series AC Issues: Climate Control System Failure

Hi there! I've got some experience working on BMWs. Had a similar issue with my 2019 BMW 5 Series diesel last summer. The symptoms you're describing sound exactly like what I dealt with. In my case, it turned out to be a faulty wiring connection to the climate control module. The workshop found that one of the plugs had corroded, causing intermittent issues with both front and rear controls. They cleaned and replaced some connections, and it's been working perfectly since. The repair cost me 95 Euro. Before you head to the workshop, could you share: How long has this been happening? Does it happen more when it's hot outside? Does the issue come and go, or is it constant? It could be the same issue as mine, but BMW made some changes in the newer models, so more details would help me give better advice. Sounds like you've got a diagnostic tool, that's great. What's the specific error code you're getting?

Thanks for your detailed response! Mine's got 158,162 km on the clock and this problem started about two weeks ago, pretty much constant regardless of the weather. The error code I'm getting is P0531. I had it serviced just last month and everything was working fine then. The issue is definitely constant, doesn't come and go at all. The AC just blows warm air, and the rear vents are completely unresponsive no matter what settings I try. Your wiring issue tip sounds promising, I'll definitely get that checked out. Did your repair take long? Planning to take it in next week and trying to figure out how long I might be without the car.

Hey again! Thanks for the follow-up info about your BMW. Ah yes, now having those extra details, especially that error code P0531, I can tell you my repair was pretty similar. When I had my wiring issue fixed, the whole thing took about 4-5 hours at the workshop. They needed time to properly diagnose everything and access some pretty tight spots. The constant nature of your problem does sound identical to what I experienced, that unresponsive rear vent situation was particularly frustrating in my case too. With your mileage being around 158k, it's quite possible you're dealing with the same wiring deterioration I had. The fact that it started suddenly after working fine during your recent service is also very similar to my experience. These issues can pop up pretty quickly sometimes. One thing I forgot to mention in my first reply, before taking it to the workshop, I tried resetting the climate control module by disconnecting the battery for about 15 minutes. Didn't solve the problem, but the workshop told me it was good that I tried as it helped them rule out some potential causes. I'd definitely recommend mentioning the P0531 code when you take it in, that'll help them target the diagnosis better than they did with mine initially. Let us know how it goes when you get it checked out!

Thanks so much for all this info! I really appreciate you sharing your experience, especially about the repair timing. 4-5 hours sounds reasonable, at least I can plan my day around that. I'll definitely try that battery disconnect trick before taking it in, though I'm not too hopeful since, like you said, it seems like a wiring issue. And thanks for the tip about mentioning the error code upfront, will definitely do that. The whole constant problem thing is driving me crazy, especially now that I'm understanding it's likely a wiring issue. Just hoping it's as straightforward as your repair was and doesn't turn into something more complicated. I'll schedule it for next week and make sure to mention everything you've pointed out. Will definitely update here once I get it sorted. Really helpful to know someone else has dealt with the same thing and got it fixed without too much hassle. Nice to know it's probably not a major system failure or anything like that. Thanks again for taking the time to help out!