The answer to 'why is my AC not cooling' is that there are several common causes, including a refrigerant leak, a problem with the compressor, a clogged air filter, or issues with the thermostat or electrical components. Symptoms may include warm air blowing from the vents, the unit running constantly, or the system not turning on at all.
If your AC is not cooling effectively, the first thing to check is the air filter. A clogged filter can restrict airflow and prevent proper cooling. You can try changing the filter yourself. If that doesn't solve the issue, it's best to call in a professional HVAC technician to diagnose and repair the problem. They can check for refrigerant leaks, compressor issues, or other problems that require more advanced troubleshooting and repairs.