Every time your indoor unit is on, the same filter circulates and recirculates the air in your home. The purpose of air filters is to keep the air that you breathe clean by removing dust particles. The problem is that clogged filters reduce the efficiency of your HVAC system and result in higher electricity bills. Your system could fail if left unattended for too long.
You can reduce your monthly air conditioning bills and extend the life of your air conditioner by changing your central air conditioning unit's air filter every six months. A three-month filter change is even better.