Technicians performed ac maintenance today. While performing maintenance we found that the system was low on refrigerant. With customer approval we activated membership for the free lb of refrigerant. I arrived and saw that the static pressure had failed testing. After performing a retest I found system to be failing with airflow as well. I showed customer and explained what that does to a system and why it was happening. We also looked to resolve allergy issues and dust in the home/system. I have a follow up scheduled with customer for Thursday afternoon between 2-3.