Over the months and years of their service, air conditioners' evaporator coils and condenser coils collect dirt. Cleaning the evaporator coil prevents the coil from becoming dirty quickly. But eventually, dirt will still accumulate on the evaporator coil. Dust reduces airflow and insulates coils, so they are less capable of absorbing heat. Make sure that you clean your evaporator coil as needed every year to avoid this problem. Watch and read this pdf to know more.