I arrived to inspected the refegerant charge on a system we recently installed. I had the homeowner turn the system on and let the system run. I found the subcooling to be operating at 12.8 deg and the system calls for 1p deg subcooling. The temperatures difference from supply to returning was 18.1 degrees. I did not see any reason to adjust the refegerant charge. This system is running and operating per manufacture specifications.