Invest in efficient equipment : Units even 5 - 7 years old are inefficient by today's standards. The graphic below shows operating cost savings based on equipment SEER ratings (governmental standards for Seasonal Energy Efficiency Ratio). In addition to savings on operating costs a strong warranty will provide peace of mind against future repair costs.

Use a quality return air filter :  Debris not caught at the return air filter soon becomes clogged in the evaporator coil. Dirty or clogged evaporator coils reduce air flow and impede system performance (effectively lowering equipment seer rating). Once clogged an evaporator coil can and should be cleaned, but the process is costly requiring lots of labor and special chemical cleaners. The picture below charts monetary savings of clean coils versus dirty ones.

* Note that the chart is based on a large home with two 5 ton systems. Savings for a single 4 ton system would be roughly $248.

Purchase a yearly maintenance agreement : An overcharge or undercharge of refrigerant will drastically reduce efficiency; even though the unit may appear to be working "fine". Having your unit checked annually will prolong equipment life as well as drastically reducing the possibility of being "caught" without a/c during the peak summer season.

Install a programmable thermostat : Programmed thermostats are capable of saving 5% - 30% on home cooling costs. AARC will install a quality programmable thermostats for $150. At that price, they can usually pay for themselves over the course of the year.

Use your bathroom exhaust fan while showering : The shower's hot water vapor adds humidity to your home which the air conditioning system has to remove before it can cool the air.

Run the range exhaust fan while cooking : One surface burner on "high" adds approximately 12,000 btu's of heat to your home. Use the vent fan on high to expel the heat before it spreads.

Use ceiling fans to move air : Ceiling fans can lower a rooms sensible temperature by 2 - 3 degrees. As an electrical  contractor AARC will happily install ceiling fans if you don't already have them..