My airflow is not cold at all. The AC unit runs a while then eventually there will be very faint warm air coming out of the vents. I had an AC guy come out to inspect the system before and he charged my AC units without trying to detect for leaks. It was running cold for a while after the freon charge but now it is not blowing cold at all. He said my coils might be leak and it would cost up to xxx to replace the coils and he recommend to replace the whole system that could cost xxxx. If the coils are leaked, is it logical/reasonable to just replace the coils or should I replace the whole system. I have personally replace the compressor fan capacitor and the blower fan capacitor last year when I noticed this issue late in the season. I am pretty handy and an electrical engineer so I do know a little about circuits. My units are 8.5 years old. What should I do? Thanks.