Upon arrival spoke with customer. Customer is explaining that master bedroom does not get strong enough airflow. Check vent damper to be fully opened. Check temperature split/ temp rise. Temperature of 120 degrees @ vent. Inspect furnace located in attic. Furnace is on running. Check motorized zone dampers voltage check. Voltage check is correct when system is call and not calling. Remove x2 zone dampers and verified that dampers open and close based on call from thermostat. Customer was made aware that old motorized damper that service master bedroom zone could possibly have an intermittent issue where zone is not also opening and closing but getting stuck in a position where damper has last failed. Newer dampers have indicator bar to show position of open or close. Damper was removed and checked during inspection of no airflow for master bedroom. Damper is operating normally @ this time. (Recommend that customer monitor airflow for master bedroom… damper may require replacement.) Cus