Common problems with existing air conditioners result from faulty installation, poor service procedures, and inadequate maintenance. Improper installation of your unit can result in leaky ducts and low airflow. Many times, the refrigerant charge (the amount of refrigerant in the system) does not meet manufacturers’ specifications. If proper refrigerant charging is not performed during installation, the performance and efficiency of the unit is impaired. Service technicians often fail to find refrigerant charging problems or even worsen existing problems by adding to a system that is already full.
~ U.S. Department of Energy