Customer has 2 y/o Goodman heat pump system that operates for main level. System is not cooling due to low pressure levels indicating refrigerant loss. Performed electronic leak search and found no leaks at evaporator coil, compressor, solder joints, connecting joints, and king valves. However, traveling down wall chaise, leak detector did go off. Noticed that several nails in the location of the line set. Informed customer that line set is possibly damaged and leak refrigerant. Recommend new line set installation with line set cover for the outside of the home.