Arrived to no heat. No power to thermostat. Found a popped 3 amp low voltage fuse. Replaced fuse and the system ran for about two minutes before popping the fuse again. Technician found two low voltage wires to the high pressure switch had rubbed and caused the insulation to wear down and expose the wire. Insulated the wires and performed function check. System ran for 30 minutes with no issues. System running and heating upon departure.