justagirl wrote:
If that doesn't work then you may want to close all your vents in the basement as your basement is most likely really cold and ,,,,,,,,.,.
Justagirl is right and wrong.
The OP should remove the register cover, reach into the duct, and confirm that the damper in the duct is open BUT, people should not close ALL of the vents / registers in basements. Regardless of location air needs to move around for it to be "conditioned" properly. Air conditioners remove heat from homes but they also remove humidity. If "all" of the basement registers are closed then the AC has no real chance to remove humidity from the basement. In basements the Air Return and at least ONE register should be open.
If the OP is in a new home and air flow from "some" registers is very weak then they should include that as an issue on a warranty list and the builder should be able to "balance" the air flow better in the home. Unfortunately the OP probably has no real evidence so the builder may dismiss the issue. I use an infra-red camera to confirm air flow at registers and it shows specific and accurate temperatures coming from each register. Yesterday at a 30 day warranty inspection of a Mattamy home I found significant air flow issues they WILL be fixed by the builder because the infra-red evidence is indisputable.
Like many of my customers say - "It's crazy not to have you in to inspect the new home, crazy."