I responded to a service call for an underperforming Carrier Infinity 19VS air conditioning unit. The homeowner stated the upstairs rooms were not cooling adequately. Upon inspection, I found the indoor evaporator coil was severely blocked with dirt and debris. I utilized a Nu-Calgon CoilShine coil cleaner and CoilShine flush 'n rinse solution to fully clean the coil. Afterwards, the system's airflow and cooling capacity were restored to normal levels. The Carrier Infinity 19VS is operating efficiently again, providing the expected comfort. Preventative maintenance like routine coil cleaning is crucial for optimal performance.