Sounds like its the control panel its self to me if its stiff exc.
Easy to replace strip the centre console to gain access then remove the plug (check this is in properly just incase) there are some cables on the control panel these just slide off if you press the tab things in (you will see what i mean) then refit a good known working one.
Can you still hear it blowing but no air??? if so could be the cable as i had this on one of my old phase1s the cable had a kink in it and made it stiff to turn the dial and didn`t always open the flap to let the heat out by the blower motor.
Easy to replace strip the centre console to gain access then remove the plug (check this is in properly just incase) there are some cables on the control panel these just slide off if you press the tab things in (you will see what i mean) then refit a good known working one.
Can you still hear it blowing but no air??? if so could be the cable as i had this on one of my old phase1s the cable had a kink in it and made it stiff to turn the dial and didn`t always open the flap to let the heat out by the blower motor.