Chas Roberts Air Conditioning Tech Tip: Change your filters once a month. Chas Roberts suggests that you change your air filters once a month to reduce strain on your system and to help your A/C unit last. It will also help with your electricity bills – a HUGE help in the midst of hot Arizona summers. As a rule of thumb, change your filters (or rinse your permanent filters) every single time you open your electric bill. For more information, visit us at http://www.chasroberts.com, or ask your technician for more details.