Why doesn't air blow after being replaced

Is the fan blowing on all speeds? If not, the resistor is burnt out and isn't any harder than the blower motor to replace. Can you select all the different air flow directions? Face, feet, defrost? The car turns the fan down while switching between those settings. A stuck blending door or actuator can keep the airflow from working properly. Have you changed your cabin air filter? Its located under the cowl so the windshield wiper arms need to be removed. If its filled with debris, the motor can't pull air in and this leads to very poor airflow. Hopefully it's not blending door related. The dashboard needs to come out to replace those parts on most vehicles.