Performed a Heat maintenance on a 1 year old Trane furnace. Checked amperage, voltage, checked for leaks, checked flame sensor and igniter. Everything tested well and system is heating properly. However, the customer complained about lack of airflow in very back bedroom. We cut in a new supply shortly after the install to improve airflow but it isn’t working. We will send installers out again to hang the duct that we added, and balance the air in order to improve airflow to back room.