Field surveys have shown that 60 percent of HVAC systems are operating below the manufacturer's specifications. Deviation from manufacturer's specifications can mean a large increase in energy consumption. For example, a 10 percent undercharge in a system can mean the loss of almost two seasonal energy efficiency ratio (SEER) rating points, and a 23 percent undercharge can mean a 52 percent loss of efficiency.

To keep their units operating at peak efficiency, homeowners are encouraged to schedule regular system maintenance. However, there are a number of problems with this approach.