Turn off the thermostat for the AC. Remove the 1/4-inch sheet metal screws from the AC heat exchanger unit with the socket wrench and 1/4-inch socket head. Peel off the foil tape along the edges. Take off the unit panel and set it aside.
Inspect the drain pan under the evaporator coils. Note any cracks or leaking. If there is a leak, you will need to have an air conditioner service technician remove the coils so that you can replace the drain pan.
Apply the air conditioner foaming cleaner directly on the coils. Allow the cleaner to rinse down the coils and enter the drain pan.
Fill a quart container halfway with bleach. Fill the container the rest of the way with water. Pour the mixture into the drain pan where the drain condensate pipe is located. This will remove any clogs from algae buildup.
Place the unit panel back onto your AC heat exchanger unit. Replace the sheet metal screws with the socket wrench. Line the edges with new strips of foil tape.