Air Conditioning - A/C Help-Poor Air Flow

HI, I have a 2 1/2 ton Payne A/C and heat pump we purchased 3 years ago brand new,in the winter time, the air that blows out the vents will blow you down, but during the summer, it barely moves. Filter is clean, coils clean, and fan is clean. What gives? My A/C runs all the time, my temp inside is ok, but I know it should be cooler. So help me to understand why the fan blows like crazy when heat is on, but not when A/C is??? And my duct work was checked,and there were no leaks. Thanks in advance...

Sounds like they hooked up high speed for heating and low speed for cooling. It should be the other way around.

Like Matt said blower speed. If you take the door off the inside unit . There should be a wire schermatic. That will show you what blower speed goes where for heat and cool