Performed diagnostic on system. Homeowner states that his nest thermostat says it has no power. Happened yesterday morning. Checked for power at thermostat and not recieving 24 volts. Went into attic and found a broken fuse. Used pigtail fuse to see if unit had a short, system tripped fuse as soon as power was restored. Troubleshoot the short down to a bad outdoor defrost board. Defrost board needs to be replaced. System is in poor condition as well as ducting has rips and tears throughout the tubes. Went over findings and recommendations with homeowner. Homeowner thought price was too much, said he has a friend in San Diego that could do it but he couldnâ€™t get him out here today. Said He will be ordering parts and doing the repairs himself. No work performed other than the diagnostic.