I think you can access some of the stepper motors from the sides. You should be able to test them from the control unit wiring harness though. Then at least you could find out which one is blocked or defective. If there was something in there blocking, I think you do have to remove the dash to get it out of the airbox.

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Olympic Peninsula, WA, USA
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2005 Mini Cooper 100k, British Racing Green/Silver-Black
04/2002 4.6is 140k, Silver/Black-Alcantara *FOR SALE*
1989 325iX 270k, Diamond Black/Black
1984 318i 370k *SOLD* (First Bimmer)
Honorable Mentions: '71 2002, '87 325, '90 325ic, '92 525it, '93 325i, '94 530i