AC fan is hitting something -And other questions

[monoblanco]

First question:
What is my AC fan hitting?

I did change the stereo, but this noise started happening months after I installed the new stereo. My question is, is there a way to remove the AC vents without pulling out the dashboard? Will i have to remove the dashboard to get to the bottom of this? I know this is pretty hard to diagnose by looking at a video. Your best guess is as good as any.

Second question:
I finally got rid of my bottle caps and installed my basket weaves today. I noticed that my bottle caps have a dark brownish residue on them. Is this break fluid residue? Is that normal? i did not care so much that my bottle caps always looked like black rims, but now that I have the nice clean weaves I want to know how to keep them as clean as possible.

[bmwstudent]

the blower motor is outside in the engine compartment. Look behind the intake manifold and you will see a removable cover plate that hides the blower motor and wiper linkage. It sounds like the blower motor squirrel cages are hitting the housings they reside in. While stuffing the radio in you might have pushed the ductwork up into the housings, simple fix. Just open up that cover plate and have a look. If you had a brake fluid leak you would lose your pedal eventually, check master cylinder reservoir for fluid, also the pedal would go down to the floor under consent braking pressure. have someone step hard on the pedal while you watch for fluid leaking at the calipers or lines.

[monoblanco]

Thank you BMW student.
I will get to the fan issue.

Is it normal to have that type of color residue on the wheels then?

I will keep an eye on them and see how long it takes for them to start getting dirty.

Thank you sir.

[Cletonius]

Is it normal to have that type of color residue on the wheels then?

Brake pads create dust with normal use. Usually a grey / brown depending on wheel color and pad composition.

Wheel wax will help keep the dirt at bay, but only by making it easier to wash off.

If you can't handle the dust, swap to full ceramic pads. Everything else will dust.