My son works on HVAC systems in Atlanta area. He told me to get the wet / dry vac and suck the water and debris out of the line where the drain line discharge is located near the outside AC unit. You will be AMAZED at all the "white noogies" and growth as he called them comes out.. (THis also pulls all the water out of the line which you should refill) Then one other idea was-- by the indoor unit, lift off the water overflow sensor from the PVC tube right near the drain outlet of the AC unit. Push a hose down the tube an inch or two and turn on the water slowly. This is best with two people. So the pressure (Around 60 PSI in most places) also helps PUSH the growth out of the tubes and also fills it back up with water. You are done.
