If your air conditioner is old, consider buying an energy-efficient model. Look for the ENERGY STAR® and EnergyGuide labels — qualified central units are about 15% more efficient than standard models. New residential central air conditioner standards went into effect on January 1, 2015; see the efficiency standards for central air conditioners for details, and consider purchasing a system with a higher SEER than the minimum for greater savings.
Not obvious is the fact that they need maintenance routinely, just like any other machine. The filter, usually located behind the front grill, needs to be washed. The condenser coil at the back of the unit can accumulate a lot of debris, and might require a special chemical bath. All air conditioning systems, large or small, need good air flow across the evaporator coil and the condenser coil. Efficiency and performance drop rapidly as air flow decreases. Lose enough air flow and the unit will burn out. Rodents can nest inside when not in use, and can foul up the unit in many ways. Wasps and hornets, as well as the honey bee find finned coils to be comfortable nesting places. Nests and dead insects can ruin the air conditioner.
Repairs—If something appears to be not working right with your heating and cooling, a professional will examine the whole health of your system. It’s easy to hop on the internet and research information to find our own conclusions, but there could be an additional component or reason why your system isn’t working properly that isn’t clear or recognizable. Consider our own health concerns—you might check out your symptoms online to try and draw your conclusions, but it’s always best to make an appointment with a doctor to receive an expert opinion.