The answer to 'best preventive maintenance' is regular HVAC maintenance. This includes having a professional technician service your system at least once a year, typically in the spring or fall. During the service visit, the technician will clean the system, inspect all components, and perform any necessary adjustments or minor repairs. This helps ensure your HVAC system is running efficiently and can catch any potential issues before they become major problems.
Preventive maintenance also includes changing your air filters every 1-3 months, depending on usage and indoor air quality. Clean filters help your system run more efficiently and improve indoor air quality. You should also clear any debris or obstructions around your outdoor unit to allow for proper airflow.