Diagnosed persistent blower motor operation in Carrier 59TP6A furnace. Utilized Fluke 116 HVAC multimeter to test control board relay, confirming stuck position. Replaced faulty Carrier HK42FZ018 control board with OEM equivalent. Inspected G wire connection at thermostat, finding loose terminal. Secured connection and verified proper signal transmission. Checked blower motor capacitor, revealing within-spec readings. Cleaned evaporator coil with Nu-Calgon 4171-75 Evap Foam to improve airflow. Recalibrated Honeywell T6 Pro thermostat. Cycled system through all modes, confirming proper blower motor operation and shut-off. Repair completed in 2.5 hours, restoring normal HVAC function.