The answer to 'why is my ductless system not cooling' is that there could be several common causes, including low refrigerant levels, a problem with the compressor, issues with the thermostat, or a clogged air filter. Symptoms may include the system not blowing cold air, the compressor not running, or the system short-cycling.
If the system is not cooling properly, first check the air filter and clean or replace it if needed. You can also check the thermostat to ensure it is set correctly and working properly. 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 tools to properly identify and fix the issue.