The answer to '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 coming from the vents, the AC running constantly, or the system not turning on at all.
In some cases, the issue can be a simple DIY fix, like replacing a dirty air filter. However, more complex problems like a refrigerant leak or compressor failure usually require a professional HVAC technician to diagnose and repair. Trying to DIY these types of repairs can be dangerous and may even void your warranty.