A clogged air conditioner drain line can cause serious problems if it is not fixed. The drain pan will fill up with water, which will cause damage to your home if there are leaks in the drain pan or the emergency overflow is clogged as well. It is smart to learn how to unclog an AC drain line before there is a serious problem.
Water Hose Method
Turn off the air conditioner unit at the circuit breaker box.
Get a water hose and take it to where the drain line is on the inside unit. The line will be either a flexible tube or PVC pipe that is connected toward the drain pan underneath the AC unit.
Have a friend go to the outside AC unit by the drain line. This way someone can relay to you when the water has broken through the clog.
Know that when a drain clogs, algae builds up and cause a slimy buildup. Water running through should break this clog up. Have the friend turn on the water hose while you hold the end in the drain. The water coming out of the hose should move the algae.
When the friend indicates that the clog has come out, have him turn the water off. Remove the hose from the drain.
Make a bleach solution of one part bleach and 16 parts water. Pour the solution through the drain from the inside opening. This will kill any leftover algae and mold.
Rent or purchase a wet/dry vacuum. From the outside drain line, use the vacuum to suck out the clog.
Use compressed air by blowing it into the outside drain line to bust the clog. This will cause a mess on the other end.
Pour the bleach and water mix down the drain line after using one of these methods as well.