Cleaning A/C drain lines

[Phisherman]

For the first time in 15 years my A/C drain stopped up. Since the drain is from the attic area then connects to another A/C in the basement I had to undo the basement line, stop it up, then blew compressed air into the line using a blow gun hooked up to my compressor. I have no idea why it was clogged or what was in there (anyone know?). After using the compressed air the water began to flow out. I was wondering the typical procedure for cleaning a (long) A/C drain line. This line is PVC pipe. A neighbor suggested using household bleach to clean it out.

[HeatMan]

Did you do this at the place where it came out of the coil near the furnace? If so, you did it right.

I usually find where the line dumps outside and use a wet vac.

[Oren]

Frogs, spiders, roaches, leaves, oh my.

Yes a bleach solution works to clear your PVC drain of cooties...

Oren

[Edwin Pawlowski]

Lint, dust, bugs, hair, and everything else that is in the air.

Yes. Pour some water to be sure it is free flowing, put a bleach solution through it on a regular basis. Someone posted before that Home Depot has a chlorine tablet made just for that and you just leave it in the pan.

[Richard J Kinch]

Compressed air on the uphill end is better at clearing than suction on the downhill end.

The recommended additives are superstitious boob-bait.

Bleach is a waste of time. The chlorine will only last a few days (assuming you even got a sterilizing dose to start with), but the high alkalinity (bleach contains a lot of lye) will stay around, and high pH fosters microbial growth.

The tablets or packets are polyquat, not bleach. The effective dose only lasts a few days, so these are also not effective.

Best technique is to flush the line clear and have an effective monitoring method. Best monitor is an overflow drain that you can easily inspect, to know when you need a clean-out.

[Phisherman]

Just a follow up to tell what worked. The A/C drain line clogged up again. I took the line off near the condenser and flushed it using a garden hose.