Check this full guide to AC maintenance for different things you can do. One of the most important things homeowners can do to help maintain their system, other than having annual yearly or seasonal maintenance done, is to change your AC unit’s air filter every 60-90 days, or 30 days if you have pets. Changing your filter on a routine basis can prolong the life expectancy of your system by reducing wear and tear on the unit, preventing blockages and improving air movement. Using a higher quality HEPA filter can also help maintain the AC system’s efficiency and minimize instances of illness in your residence.