BMW Z3 Climate Control Dead, Solar Sensor Issue?

Hi there! I'm a weekend DIYer with some experience working on BMWs. Had a similar issue with my 2002 BMW Z4 last winter, and my also went through this with his 3-series. The symptoms sounded just like mine, climate controls not responding and heating issues. Turned out to be a loose connection at the control module. Took it to my regular workshop, and they found that the wiring harness connector was corroded and needed cleaning and reseating. Total bill came to 95 Euro for diagnostic and repair, which wasn't too bad considering I was worried it might be the whole control unit. Could you share some more details about your Z3? Has the check engine light come on? Also, when did you first notice these symptoms? This could help determine if it's the same issue I experienced. By the way, in case it's different from what I encountered, it would be smart to have them check the entire HVAC system while they're at it.

Thanks for sharing that experience! Dealing with a similar headache on my Z3 right now at 145811 KM. Got it serviced just two months ago but this climate control issue just started last week. No check engine light yet, but the heating is super inconsistent, sometimes works fine for like 10 minutes then just gives up. Your wiring harness issue sounds pretty similar to what I'm experiencing. I was dreading having to replace the entire control unit, so hearing that it might just be a connection problem gives me some hope! That repair cost sounds way better than what I was expecting to pay. Definitely going to have my mechanic look at those connections first. Did your car have any other weird electrical glitches before you got it fixed? Mine's been acting a bit funky with the power windows too, so wondering if it might all be related.

Hey again! Thanks for those extra details about your Z3. You know what's funny? When I had that wiring issue with my Z4, my power windows were actually acting up too! It's like these BMWs love to throw electrical gremlins at us all at once. Those symptoms you're describing are really ringing bells for me, especially that part about the heat working for a bit and then giving up. Mine did exactly the same thing, and it was driving me nuts before I got it sorted. With that mileage on your Z3, it's pretty much exactly when these kinds of issues start showing up. Here's something I didn't mention in my first reply, after they fixed the wiring harness on mine, they found that there was some moisture that had gotten in there over time. That's what caused the corrosion in the first place. Might be worth asking your mechanic to check for any signs of moisture damage while they're poking around. The power window thing definitely sounds related, these electrical gremlins tend to travel in packs! Once they cleaned up my connections, both the climate control and the unusual electrical quirks cleared up. Just make sure whoever looks at it is familiar with BMW electrical systems, they can be pretty finicky. Want me to know how it turns out? Always good to know what fixes work for these older Bimmers!

Thanks a lot for that additional info! That's super helpful to know about the moisture issue, definitely going to mention that to my mechanic. It's actually really reassuring to hear that fixing your wiring sorted out both the climate control and the power window problems. Makes total sense that they could be connected. I'll make sure to take it to someone who knows their way around BMW electronics. Got an appointment scheduled for next week, and I'm feeling much more confident now about what to expect. I'll definitely let you know how it goes, really appreciate all your help and experience with this! Fingers crossed it's just the wiring harness and nothing more serious. Thanks again for taking the time to share your experience. It's saved me a lot of worry about potentially having to replace the whole control unit. Will update you once I get it checked out!