It seems apparent to close Heating and Air Conditioning registers when indoor temperature control is an issue.
You can keep the rest of the home comfortable and save money by not wasting heating and cooling in rooms you don’t need, but unluckyly, it’s not that easy; Heating and Air Conditioning units and HVAC duct systems are designed to give a identifiable volume of air to each and every room based on its square footage, however one or more registers can affect that careful equilibrium.
Heating and Air Conditioning systems don’t think whether all registers are open. Until the temperature control setting is reached, it produces the same amount of heated or cooled air and consumes the same amount of energy, then each room’s supply air volume is controlled by internal dampers inside the branch ducts, then in this way, consistent hot and cold temperatures are diagnosed whether a room is close to or far from the blower, then when a single or more supply registers are closed, airflow balance and hot and cold temperatures are disrupted, rooms closest to the blower may earn too much airflow, while rooms farther away may not, but closing supply vents increases static pressure inside the supply HVAC duct, which in turn stresses the idea blower, potentially leading to a shorter service life of that component.