"The most important part of HVAC maintenance aspect is maintaining unrestricted air flows. Dust, dirt, and debris are an HVAC system’s worst enemies. Whether it’s an indoor or outdoor unit, you must keep all filters clean and heat exchangers and coils free of restrictions. We recommend that your heating and cooling system be checked and serviced twice a year; ideally a spring and autumn tune-up. Also we recommend that you change your filter regularly, depending on the type of filter you have. This alone can eliminate many of the most common problems that need fixing and can significantly reduce the likelihood of a serious breakdown. "