Tom, in reference to the AC, see if someone is familiar with HVAC and have them look for balancing dampers in the duct work itself. Trying to force more air into another area by blocking the vents is the worst way to try getting more into another space. If you can locate dampers, if installed, you can open/close or partway to increase/decrease airflow. They will have wing nuts and a small handle which operates a piece of metal that can close off the duck or go anywhere from full open to full close. Look for them on the takeoffs of the main duct line. Depending on when and how the duct was installed you should see the main line reduce as takeoffs come into play to maintain the air pressure all the way down the line. Air duct pressurizes by traveling all the way to the end and then back pressure. Common mistake is a duct outlet at the end of a duct. Makes back pressurizing a bit more difficult and the air flow much louder. If you can follow the duct from the equipment you should have the main line run with smaller duct coming off to feed rooms/areas and at that takeoff there should be a balancing damper. You can loosen the wingnut and either open the damper more or close it some but always mark the initial position just in case you need to go back. Ideally you'd have a HVAC guy there doing this by taking airflow measurements and adjusting these dampers but you do what you have to. Blocking the returns can be a problem depending on how closely they were sized. They may end up restricting airflow back to the system.