Blown low voltage fuse on furnace control board due to cut in half thermostat wire at floor level in the hallway Replace 10 ft of 18/8 thermostat wire from first floor hallway thermostat location into the crawl space and patch to the existing 30 ft run back to the furnace Run test fan mode and cooling mode and set to 72 Honeywell T4 installed with furnace SN: 2433