1998 Chev Venture - HVAC - Blocked AIR FLOW

Greetings

when I put the HVAC fan on full output there is virtually no air coming from the vents - the position dial does not change the vent position.
How shall I precede in fixing the dial - or I need to fix the Vacuum system also?

This is what I know:
Good: Fan works fine
Good: I changed the cabin filters
Bad: control switch does not switch vent outlet
Bad: Hot air is blowing at 5% rate from all vents as if the line is blocked somewhere

Please help! Winter is coming and I am cold
Thanks!