The answer to 'why is my evaporator coil not cooling' is that there are several common causes, including a refrigerant leak, a blocked airflow, or a problem with the compressor. Symptoms may include the coil icing up, the air conditioning not blowing cold air, or high energy bills.
If the evaporator coil is not cooling properly, the first step is to check for any visible signs of damage or leaks. You can also try cleaning the coil and checking the air filter. However, if the issue persists, it's best to call a professional HVAC technician to diagnose and repair the problem, as they have the expertise and equipment to properly service the system.