Customer explained how heat pump was not cooling. Fuse was failed on furnace. Low voltage wiring looked to be in ok shape. Found the R wire on control board on heat pump, with missing insulation that was exposing the copper part of wire. It is possible that the wire had touched the metal cabinet causing system to blow fuse on furnace. I replaced fuse and repaired wire and then performed a tune up. AC precision tune up. Clean and tune up AC; cleaned condenser coil, checked all outdoor electrical components, tested indoor air flow, checked refrigerant levels, and tested overall AC operation. Motor starter is very pitted. Checked ohms on it, it is in range at this time. If fuse fails again, replacing the low voltage wiring would be next. All other sensors and pressures switch wiring are fine. System is also low on refrigerant. Can’t guarantee that system will maintain temperature based on the issues found, system could also freeze up. Added 1pd of refrigerant. Factory charge is 10lbs. D