Air filters are an important part of your home's HVAC system and can help improve your indoor air quality. In fact, according to the EPA, a clogged AC filter "can cause airflow restriction and increased pressure drop across the evaporator coil." This can lead to higher energy bills and even... Air filters are an important part of your home's HVAC system and can help improve your indoor air quality. In fact, according to the EPA, a clogged AC filter "can cause airflow restriction and increased pressure drop across the evaporator coil." This can lead to higher energy bills and even...