Performed AC cool check. Checked the electrical, mechanical, safety, and performance of the system. I cleared the condensation drain line and flow tested the drain with water. I also treated the drain line. The condenser coil was cleaned. The air handler, evaporator coil, and blower wheel are dirty. There is significant biological growth inside the system. The blower motor capacitor is below value. The system was cooling but was only cooling at 2 degrees of sub cooling. This is below the factory spec of 12 degrees. I went over what I had found with the homeowner and spoke to him about the existing issues and age of the system. The system was running at the completion of service.