The customer had another company out completing a maintenance inspection and found the system with a low Subcooling. Found that the Subcooling was at 5 degrees when the system calls for a 12 degree Subcooling. Added 1 pound of 410a to get the system at the designed sub cooling of 12 degrees. Unable to find a leak at this time. I would recommend having us come back out before the first years warranty is up to recheck the system to make sure there's no leak.