Complete 2 system a/c repair and preventative maintenance check. Customer says water is coming from a backup drain line above the back door. Checked systems, found both primary drain lines clear, free of clogs and draining properly. Found no water in pans where backup lines are connected to, both are bone dry. Cleared backup drain lines with nitrogen. Tested refrigerant levels and they are good. Downstairs filter was slightly dirty so went ahead and changed it. Most likely water customer was seeing was residual water in the backup drain line from the previous issue. Found no issues. Both systems are cooling and draining normal at this time.