my AC wasn't blowing cold. when i took the cap off the condensate drain line it was full of water. i have a 6 HP shop vac with an attachment to prevent air leakage. the first time i sucked everything out the water was dirty. the next day it wasn't draining again. i sucked everything out again and next day it wasn't draining again. the next time i sucked everything out i left the vac on and poured some water through the line. the water went right through it and came out clean. i don't think the line is clogged. i can feel a high rate of air flow when i stick my finger in the line. i'm wondering if there could be another reason for it not draining. i'm in a condo on the second floor. i do not see a trap or pump. any suggestions? pics in link.