Blower making new noise.

I've a '98 Astro with 145,000 KMs. The blower was fine and then suddenly the enxt day it starts to make a BRRRRRR type noise. Like a constant helicopter blade type noise. Its not very loud and livable, but all the same it suddenly started and obvious. Its a steady noise, and remains the same pitch and loudness as it did when it suddenly started 2 weeks ago. Its never gotten any worse.
You can hear it loudest at all times from the defrost vent in the middle of the dash. Even when its set to floor. I assume since its the nearest direct route for the noise to travel.

It started immediately, not like it was gradual.

The selector works ok for defrost, vents, heat, heat/defrost, etc. It blows out of all the right places at the right times. It comes on and I can change speed perfectly, of course the noise will speed up and get slightly louder with the higher speeds.
Its some consistent noise from the fan in there.
Sort of thing you'd think theres a leaf stuck in it, although I can be sure its not. Its made the same exact noise and never changed for 2 weeks....if something was rubbing against it you'd expect it to wear off, or change pitch up and down as it jiggles or moves...???
To think "bearings" is hard to believe since this started overnight.

How do you even get in to look at it?

Is there common issues?

Is there perhaps a door thats maybe not open/closed somehow? because this sounds like a consistent air blowing against something in the way type noise, although it does go to the right places at the right times and blows as strong as ever. When its set on heat (floor) it never blows from the defrost, and vice versa....so that gives me the impression all doors/flaps are working.

Thanks a lot for any help.
:tongue:

I could be bearings and yes they go just like that,or could be a lump of sour 'coon shit stuck in there,one of my dads favorite lines.Depending on where you live it could be the dreaded House of Mouse,they love to hide in heater boxes for some dumbass reason.