Arrived on site to perform maintenance on 9 year old system. Upon arrival, homeowner mentioned that system feels as if it is not cooling correctly. He had another company come out about a week ago and found his unit low on refrigerant and They charged it up with refrigerant. Advised that we should start with diagnostic today Before performing maintenance. Had customer cycle system for cooling. System kicked on, but is not blowing cold air. Checked outdoor unit and found unit is almost flat on refrigerant. Unit lost almost 10 poundS of refrigerant in about a week. Visually inspected condenser coil for any signs of oil residue, nothing found. Went into attic and opened up coil compartment to visually inspect evap coil. Primary drain pan underneath evap coil is covered in oil residue. Evap coil is leaking refrigerant. Looked up all style coil warranty and found evap coil is no longer under warranty. Also due to how unit is installed, there is a 2x4 running across evap coil compartment whi