A/c blower/ fan running hard but only medium air coming out
 

I have a 2000 Volvo S 80 and I'm having problems with the A/C blower fan and little to med air coming out. It sounds like it's running very hard a lot of fan noise in the center of the dash, with the control turned to high. But only a little to medium air coming out of the vents. The AC also feels cold. Was wondering if maybe it was a vacuum problem or door not opening all the way? Also replaced cabin filter about a year ago. Any ideas? Thanks