I was called out to your home for an air conditioning system not working. You explained to me that their is black stuff in the return is growing in your return. During my evaluation I determined that the air conditioning system has does have growth in the return of the unit. I also went through the entire system while I had everything already open and did a complete system evaluation and discovered some potential issues and determined that you would benefit from some system improvements due to the age of the system and for the sake of your family’s health, safety and well being in mind. This estimate includes -installing a Uv light kit -seal duct work and clean out any black stuff in the return Thank you for choosing Kings Electric and Air Conditioning! We hope to hear from you soon so we can get started right away!