BMW 1 Series AC Failure: Heat Sensor Mystery

Hey there! I had a similar issue with my 2019 BMW 2 Series diesel last summer. The symptoms you're describing match exactly what I experienced, complete AC failure and control unit not responding. Initially thought it was just the temp sensor too. Took it to the garage and turned out the AC control module itself was faulty. It wasn't just a sensor problem, the entire control unit needed replacement. The unit was completely dead and wasn't sending proper signals to the AC components. Not trying to worry you, but it's a fairly serious repair as it's a central component. The mechanic had to order the part specifically for the car. The whole job took about a day and a half at the garage because they had to remove quite a bit of the dashboard to access and replace the unit. The good news is that once replaced, everything worked perfectly again, all the automatic controls, temperature regulation, everything. Haven't had any issues since then. Hope this helps with what you might be facing.

Thanks for sharing your experience! That's really helpful as it sounds exactly like what I'm dealing with. I'm hoping to get my 1 Series fixed soon. Since you had the same repair done, do you remember roughly how much it set you back? Also, has everything been running smoothly since the repair, or have you noticed any other quirks with the AC system?

Hey again! Really glad I could help! Just to update you, I actually got my car fixed last week. You were spot on about it being the temperature sensor at the heat exchanger, and they fixed that up no problem. But yeah, just like in my case, the main culprit was indeed the AC control unit, it was completely shot and needed replacing. The total damage was 980 € for the control unit replacement. Trust me, I know it's not cheap, but considering how crucial the AC system is, it was worth every penny. Since getting it sorted, my 2 Series has been running like a dream, the AC is working perfectly, no more error messages, and the automatic climate control is as smooth as butter. I just keep thinking back to when I first had these issues and how worried I was. But honestly, once you get it fixed properly, you'll forget you ever had problems. The key is getting it done right the first time, which it sounds like you're on track to do. If you're planning to get it repaired soon, I'd say go for it. The peace of mind alone is worth it, especially now that summer's coming up. Let me know how it goes!

Just got back from the mechanic and wanted to close this thread. The repair went better than expected! The technician was super thorough and found that my AC control unit was indeed fried, just like yours. Theyaged to source a compatible unit pretty quickly, which was a relief. The whole thing cost me around 850 €, which was actually less than I'd budgeted for after seeing your repair cost. They threw in a basic AC service too, which was a nice bonus. The mechanic showed me the old unit, it was completely dead, no wonder nothing was working! Got to test drive it on the way home, and wow, what a difference! The AC is blowing cold again, all the controls are responding perfectly, and those annoying error messages are gone. Feels like I've got a new car! Thanks again for your help. Really made me feel better about getting it sorted, especially after my previous bad experience with mechanics. Now I can finally enjoy driving without worrying about the AC going crazy!