BMW M3 Climate Control Woes: AC Not Working & Error Code

Hey there! I've had some experience working on cars and faced something very similar with my 2015 BMW M4. The symptoms were almost identical, climate control acting up and rear vents not working properly. After taking it to my regular workshop, they found it was just a loose connection in one of the cables going to the ventilation control module. The connector had worked itself loose over time and was causing the system to malfunction. The fix was pretty straightforward, they reconnected and secured the cable properly, costing me 95 Euro for the diagnostic and repair work. To help you better, could you share: Have you noticed any clicking sounds when changing ventilation settings? Does your AC work fine in the front but just not in the rear? Did the issue start suddenly or gradually get worse? I've also owned a BMW M5 and these cars can have similar ventilation quirks, so I might be able to offer more specific advice based on your answers.

Thanks for sharing your experience! My issue is a bit different though, mine started with a faint rattling noise before the rear vents stopped working completely. I had my last service just 2,500 KM ago but didn't mention this issue then as it wasn't happening yet. Currently at 155376 KM and no clicking sounds, just complete failure of the rear vents and weak cooling overall. The problem got worse over about two weeks. Made an appointment with my mechanic, but wanted to gather some insights from the community first to know what I might be dealing with. Good to know it could be something as simple as a loose connection though!

Hey again! Based on what you're describing now, especially that rattling noise before complete failure, I'm thinking this might be a bit different from my previous cable connection issue. In my M4, when I had a similar rattling followed by failure, it turned out to be the actual flap motor that had worn out. The plastic gears inside had stripped, which explained the rattling sound before it gave up completely. My mechanic ended up replacing the entire flap motor assembly, and it sorted everything out. It was more expensive than my previous repair, around 380 Euro including labor, but it's been working perfectly for the past 18 months now. Since you're at 155K km, it's pretty common for these parts to wear out. The weak overall cooling you're experiencing also matches what I went through, when the flap motor fails, it can't properly direct the airflow, affecting the entire system's efficiency. Definitely have your mechanic check the flap motor first. If you're lucky, it might just need a good cleaning and lubrication, but be prepared for a possible replacement. These BMWs are amazing machines but their HVAC components can be a bit finicky at higher mileages. Let us know what your mechanic finds! Always good to share these experiences for other owners.

Thanks so much for the detailed response about the flap motor! That really helps narrow things down. The symptoms you described with your M4 sound exactly like what I'm experiencing now. The rattling followed by complete failure matches perfectly, and it makes sense about the plastic gears being the culprit. I'll definitely mention this to my mechanic when I take it in next week. I was honestly worried it might be something much more serious (and expensive), so hearing that it could be fixed with a flap motor replacement for around 380 Euro is actually a relief. Given my mileage, it does make sense that these parts would start wearing out. Just hoping it hasn't caused any additional damage since I've been driving it like this for a couple of weeks. Really appreciate everyone's input here, it's super helpful to hear from other BMW owners who've dealt with similar issues. I'll update the thread once I get it looked at and know exactly what the problem is. Fingers crossed it's just the flap motor!