Performed single system cooling maintenance. I checked amps, filter, electrical, drains, cleanliness, temperature differential, refrigerant temperature, and washed the outdoor unit. The system is performing within manufacture specifications. To prepare the drain for cooling season, it is advised to perform a drain treatment. This is an attempt to prevent clogging from occurring. Customer said that her allergies have been bothering her lately and that the filter probably just needs to be changed. Upon observation, it was determined that the filter has minimal build up. I replaced the filter. I offered to upgrade the filtration and an air cleaning device (air scrubber).