The answer to 'how to fix AC' is to first check the air filter and clean or replace it if it's dirty. Next, inspect the outdoor unit and clear away any debris or vegetation around it. Then, use a garden hose to gently clean the condenser coils. If the unit is still not cooling properly, you may need to have a professional HVAC technician inspect the system for any refrigerant leaks, electrical issues, or other problems.
Maintaining your air conditioning system with regular tune-ups and cleaning can help prevent many common issues and extend its lifespan. It's generally recommended to have a professional service the unit once a year, before the start of the cooling season.