"ken" wrote in message
oups.com...
Our new central a/c unit does not do much to cool our second
floor...We live in an old house and the ductwork apparently can't
handle the job too well.

Try closing the 1st floor registers. This should force the cold air to the
2nd floor, where it will drift down and still cool the 1st floor. Of
course, this is just temp solution until you can get it fixed correctly.