The answer to 'evaporator coil not cooling' is that the most common causes are a refrigerant leak, blocked airflow, or a malfunctioning blower fan. Symptoms include warm air coming from the vents, the system not cooling effectively, and high energy bills. Solutions may involve repairing leaks, cleaning the coil and air filters, or replacing the blower fan.
If the issue is a refrigerant leak, it's best to call an HVAC professional, as they have the proper tools and expertise to safely diagnose and repair refrigerant leaks. Cleaning the coil and replacing air filters are typically DIY tasks, but if the problem persists, it's wise to have a technician inspect the system.