Quote:
Originally Posted by Dim73
1. Yes, it's like that but it doesn't get louder when I increase the fan speed manually. On the contrary, after the 3rd fan speed setting (3 bars displayed), I can't hear it.
2. It has to do with the A/C. It happens only when it's on and it sounds like a fan reving up.
3. Hmm, I think it's in manual. I'll check it out.
4. I haven't thought about that! I guess a faulty bearing would make much more noise, which would continue, at least at medium speeds. This noise disappears in a few seconds (or I can't hear it after a few seconds). Is there a way to confirm it's the caliper (e.g. if I press the brake pedal a few times)?
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1. I have known blower fan bearings make noise at low speed but go quiet when speed is increased, still worth letting BMW look at it imo.
2. It could be a little noise from the A/C compressor as it cycles, maybe a little irritating but not a worry.
4. A wheel bearing would be more of a grind/rumble at speed, possibly changing tone then cornering as the bearing is loaded. To see if you have a sticking caliper jack up each end of the car in turn so the wheels are free and turn them by hand. Any catching will be easy to feel / hear.
The fact the noise stops can be for a few reasons such as the caliper being slow to release or the pad wears slightly until it clears the disc. Worse is a binding caliper and you would spot this after a drive as the smell is unmistakable so I don't think that is your problem.