This is a newly constructed house, and there should be some kind of warranty involved. The installing contractor should take full responsibility and make this right. The homeowner bought a new home with a new heating and cooling system that
the builder said would do a good job, and now he should make it right.
JMN, I apologize for someone in our industry giving you an unsatisfactory product (whatever the reason).
1) Complain to the builder and don't back down - keep at them
2) Go to your city inspectors and make them aware of the poor performance
3)Complain to Better Business Bureau
4) Do the legal thing if necessary
I know I am gonna get hit because builders force us to take the cheap way, but the basics HAVE to be followed.