Air conditioning units typically include a condensation drain pipe. The purpose of the drain pipe -- or line -- is to drain the condensation from the air conditioning unit to the outside of your home. If the drain pipe becomes clogged with debris, mold or mildew, the condensation will not drain properly and the water could back up into your home. Regular maintenance and care of your unit, at least once a year, are important to keep it working correctly.
Turn off the air conditioning unit at the thermostat.
Remove the front panel from the unit. If the panel on your unit is secured with screws, remove them with a screwdriver.
Locate the drain line near the end of the drain pan, below the condenser coil. The condensation drain pipe should start at the air conditioning unit and exit outside your home.
Disconnect the drain line.
Attach a garden hose to the drain pipe. The hose opening might be too big for the drain line. If this is the case, purchase a nozzle attachment to place on the hose.
Turn on the water to the hose for a few minutes to flush out the pipe. Turn the water off. Disconnect the hose from the drain pipe.
Mix equal parts household bleach and water in a container.
Pour the bleach-water mixture down the drain line.
Allow the bleach-water mixture to sit inside the drain for 15 minutes.
Reattach the hose to the drain pipe. Turn the water on. Allow the water to run through the drain pipe to rinse out the bleach mixture.
Reattach the front panel to the unit and turn the power back on.