Beemer gurus,Please help!

I recently bought 740i 94' with some heating/air con problem.

when i turn the blower switch on,I can hear the fan noise but no air from the center vent. previous owner told me heating/air are working except no air from center vent. So I changed stepper motor which didn't help.
Shouldn't I be able to see vent flops moving when i swtch on?
Just blower noise without air coming out of the vent.
What should I check?

Thanks.

CK

Possibly need to replace blower/resister, aka final stage.

http://shrubbery.student.utwente.nl/ has a lot of info about the heating and air conditioning of an E32.