The first step in fixing an AC unit leak is to identify the source of the leak. This can be done by visually inspecting the unit and checking for any signs of water damage or corrosion. If the leak is coming from a pipe or hose, it may be necessary to replace the part. If the leak is coming from the condenser or evaporator coils, it may be necessary to clean or replace them. Additionally, it may be necessary to check the drain pan and drain line for any blockages or clogs. Once the source of the leak has been identified, the necessary repairs can be made. It is important to ensure that all parts are properly sealed and that the unit is properly insulated to prevent future leaks.