1992 BMW 525 Noticibly less air from ac than vent at same f

When I switch from Fan to AC, there is much less air coming out of vents.

Volume of air is so low that it is unable to cool car in summer even though it comes out cool.

Are there baffles that may be blocking the flow? I hear the blower moving air.

Where do I start? and were are the baffles or valves I hear when I switch the AC on?

Thanks,

MJ