HARD FAULT: In-cabin Ventilation Fan Tied to Ignition. Won't Turn Off with Controls.

[maniz]

On a service visit to the dealership earlier this week regarding some issues I've been having with the auto-trunk release, their re-programming of the car's electronics somehow ended up affecting the interior fan/blower such that it turns on/off with the ignition ONLY. The in-dash buttons can be used to increase/decrease its speed, but not to turn it off; whether by holding down the decrease button or gradually minimizing it all the way to off.

A/C, recirc etc. all operate as usual.

The foreman is quite knowledgeable and has been giving me detailed updates over the phone, but the issue has him and his techs flummoxed. They acknowledge their initial programming to address the issues with the trunk must've caused it but they don't know how; their module-by-module analysis of the programming parameters has not turned up a setting that could've been left on or off accidentally.

They have now reprogrammed all modules to the latest I-STEP again (was last done just 3 weeks ago) but are stating this has turned into a HARD fault, where software changes are not affecting it. They will try swapping a specific HVAC resistor from a donor car off the lot today and if that doesn't work, they will open a case with BMW.

I thought to ask here in case somehow has experienced this with a modern BMW before and what ended up being the cause.

On a side note, the loaner X3 M40i isn't half bad, as much as I despise the M brand dilution...

[milk242]

I do remember when flashing my car to the latest software revision my fan would just stay on and I couldn’t turn it off. I believe it had something to do with a recalibration procedure. I think people say the a/c light should be blinking but my mine did initially and it didn’t anymore but still couldn’t turn it off

I believe I just kept driving it around to places until it worked.

[maniz]

Originally Posted by milk242

I do remember when flashing my car to the latest software revision my fan would just stay on and I couldn’t turn it off. I believe it had something to do with a recalibration procedure. I think people say the a/c light should be blinking but my mine did initially and it didn’t anymore but still couldn’t turn it off

I believe I just kept driving it around to places until it worked.

Interesting to hear you say that because after the dealer troubleshot the issue with BMWNA for roughly a week and exhausted all software fixes, BMWNA asked them to replace my ventilation master control unit which they are shipping from Germany and would take 7-10 days to arrive. So the dealer's foreman asked me to pick up the car while waiting on the part to come in.

I went to pick it up, got in the car when the service valet pulled it up, and the blower was off. Surprised, I turned it on, and it did. Then off, which it also did. It was 100% back to normal entirely on its own! I called the foreman over and he was baffled because the issue was present until that night before when BMW ordered the part for me.

The master control unit should be in this week and I will get it replaced anyway as a precaution, but thanks for sharing your feedback. If it is simply about re-calibration, I am surprised BMWNA had no idea how to do it, or perhaps they did but couldn't get it to work.