BMW Z3 Heat Not Working? Troubleshoot Before Winter

I dealt with a similar issue in my 2005 BMW Z4 last winter. Initially thought it was something major, but turned out the control module's wiring connector was corroded and had a loose connection. The heater valve wasn't getting the proper signals. The mechanic cleaned the connector pins and secured the plug properly, no more heating issues since then. It wasn't a serious repair, just needed thorough diagnostic work to pinpoint the exact problem. Much better than replacing parts unnecessarily. Worth checking the simple things first, electrical connections often cause these symptoms, especially in cars of this age. My previous mechanic wanted to replace the entire heater valve assembly before I got a second opinion. Hope this helps with your troubleshooting.

Hey, thanks for sharing your experience! That's really helpful information about the control module wiring. I'm dealing with exactly the same symptoms right now. Do you remember roughly how much you ended up paying for the diagnostic work and repair? Also, has everything been working fine since then, or have you noticed any other heating quirks pop up? Just want to make sure I'm prepared in case there's more to it.

Hey there! Just wanted to follow up, glad I could help with the wiring info. Since we last chatted, I actually had my car looked at again because I was still curious about that water valve. Turns out my initial hunch was partly right, they found it was indeed defective and fixed it along with that cable connection issue I mentioned before. The whole thing came to 95 € for sorting out the faulty cable and plug connection. I know that might sound like a lot for what seems like a simple fix, but honestly, it was worth every penny. The heating's been working perfectly since then, no more cold spots, no more inconsistent temperature, nothing. I've put quite a few miles on the car since the repair, and everything's still running like a charm. The passenger side heat is just as strong as the driver's side now, which is such a relief. Sometimes it's just good to get everything properly sorted, you know? Let me know how yours works out!

Thanks for the detailed follow-up! I actually just got back from the mechanic today. You wouldn't believe it, but I had almost the exact same combination of issues. The mechanic found both a corroded wire connection and a failing water valve. The good news is they fixed both problems in one go. The total bill came to a bit more than yours, about 150 for parts and labor, but honestly, it was totally worth it. The heat's working perfectly now, even on the passenger side. It's such a relief not having to deal with that weak airflow anymore. Guess I was right to get a second opinion instead of jumping straight into major repairs! Really appreciate everyone's input on this. It's great having knowledgeable people to bounce these issues off of. Will definitely keep an eye on things, but for now, I'm just happy to have a properly working heater again.