The answer to 'central air 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 ductwork. Symptoms may include warm air blowing from the vents, the system running constantly, or high energy bills.
For minor issues like a dirty air filter, you may be able to fix it yourself. However, for more complex problems like a refrigerant leak or compressor failure, it's best to call in a professional HVAC technician. They have the expertise and equipment to properly diagnose and repair the issue to restore your cooling.