Service diagnostic found that the condensation drain line was clogged. Water was running into the secondary drain line and filling the secondary drain pan. I also found that the secondary drain pan was rusted, the blower wheel was dirty, the condenser fan motor showed signs of overheating and the contactor on the condenser unit was burnt and pitted. The heat exchanger for the furnace is starting to rust. I spoke to the homeowner and went over the issues I found. I also discussed the condition and age of the system. She chose to have the drain lines cleared and the water removed from the secondary pan. I cleared the primary and secondary drain lines and flow tested the drains with water. I also treated the primary condensation drain line. I removed the water from the secondary drain pan. I then function tested the system. The system was running at the completion of service.