The answer to 'air conditioner not cooling' is that there are several common causes, including a dirty air filter, low refrigerant levels, issues with the compressor or condenser, or problems with the thermostat. Symptoms may include warm air blowing, the system cycling on and off frequently, or the unit not turning on at all.
In many cases, simple DIY troubleshooting and maintenance can resolve the issue. However, if the problem persists or you're unsure of the cause, it's best to call in a professional HVAC technician to properly diagnose and repair the system. They have the expertise and tools to identify and fix the root cause, ensuring your air conditioning unit is running efficiently and effectively.