The answer to 'why is my air conditioner not cooling' is that there could be several common causes, such as a refrigerant leak, a problem with the compressor, or a clogged air filter. Symptoms may include warm air blowing from the vents, the AC unit running constantly, or the system freezing up.
Some potential solutions you can try yourself include checking and replacing the air filter, cleaning the outdoor unit, and ensuring the thermostat is set properly. However, if the problem persists or you're not comfortable troubleshooting the issue, it's best to call in a professional HVAC technician to diagnose and repair the issue.