Thanks for the info. I did remove a few outlets and looked in the ductwork with a mirror. I did not see much, but it looked open and connected. My registers cannot be closed, I can only turn them to change the air flow direction.
I've tried to speak with a tech at Keystone who knows how the system was designed, but Keystone won't let me talk to those people. Keystone has told me several times that they are willing to help the dealer, but the dealer needs to contact them. I can't get the dealer to simply call Keystone.