Shut off your air conditioner unit and unplug it from its power source.
Locate the hole in the copper piping and use your pipe cutter to cut a section of pipe that covers 1 inch on either side of the hole. Remove the section of pipe.
Sand the outside edges of the pipe openings you have just cut.
Clean any corrosion out of the interior of the pipe openings with a wire brush.
Brush flux onto the surfaces of the pipe openings as well as the ends of the copper sleeve.
Fit the copper sleeve over the pipe openings.
Put on your safety goggles and turn on your torch. Hold the tip of the torch flame to one side of the copper joint and the tip of your solder wire to the other.
Torch the joint until enough of the solder has melted over it to cover it completely. Repeat with the remaining joints and let the tube cool.