How to unclog the air conditioner drain line

When the pipe that drains condensate water from the evaporator to the outside of your home gets clogged, follow the steps in this repair guide to clear the condensate drain.

You may hear water dripping or see water seeping from the floor under your inside air conditioner unit when the drain pipe gets clogged. The air filter may also get wet as condensate water backs up in the drain pan under the evaporator.

Many central air conditioners have a drain float switch that shuts the system down if the drain is clogged and water backs up under the evaporator. If this switch trips, the air conditioner will shut down to avoid water damage.

If water drips from below the inside air conditioner unit and/or the air conditioner shuts down because the drain float switch tripped, then it's time to unclog the drain line.

Instructions

1. Disconnect electrical power

Shut off the house circuit breaker for the HVAC unit to disconnect electrical power.

Wear work gloves to protect your hands.

2. Pull off the condensate drain float switch

Pull the condensate drain float switch to remove it from the drain system.

Set the drain float switch aside. The switch has wires connected to it. Don't disturb the wiring connections as you set the float switch out of the way.

3. Vacuum out the drain line

Use a wet/dry vacuum to suck water and clogs out of the condensate drain line.

You can vacuum water and clogs out through the opening for the float switch, the vent hole and the drain pipe outside your home.

If you're able to remove the clog and water flows freely through the drain pipe, you don't need to use the plumber's snake to clear the drain line.

4. Snake the drain line

Use a plumber's snake to clear clogs from the AC drain line.

You can run the plumbers snake through the opening for the float switch, the drain vent and the drain line outside your home.

If you're not able to clear clogs in the drain line, have a plumber or service technician clear the drain.

5. Pour bleach down the drain line

Position a drain pan under the drain line at the outside of your home to protect the grass or other vegetation.

Don work glove if you don't already have them on.

Insert a funnel in the drain line vent.

Pour 1 cup of chlorine bleach down the drain line vent to prevent future clogs.

Remove the funnel.

Safely dispose of the chlorine bleach that goes through the drain line and collects in in the drain pan outside your home.

5. Restore electrical power

Reset the house circuit breaker to restore electrical power to your HVAC system.