AC in the attic is draining.

[oktx]

I noticed it was draining through the drain and onto the back porch. Last time this happened it overflowed and damaged the drywall on the kitchen ceiling. We pour bleach in the drain hole about every other month to keep it clear. Why does it do this and what causes it? Thanks!

[Olphart]

Bleach really doesn't do anything (or enough). You need to take a portable air tank up and blow out the normal drain AND the emergency drain. This is especially true if you have blown in insulation. Dust, insulation and possibly mold to some degree clogs up the normal drain.

[oktx]

Bleach really doesn't do anything (or enough). You need to take a portable air tank up and blow out the normal drain AND the emergency drain. This is especially true if you have blown in insulation. Dust, insulation and possibly mold to some degree clogs up the normal drain.

So the drain out side is the emergency drain?

[thegrouse]

That is generally a secondary drain designed to alert the homeowner that the primary drain is plugged up. They drain over doors or windows to be seen. AC units create condensation and it has to be drained. Many times mold and sludge builds up in the drain lines from junk in the air that ends up on the coil and from stagnating in the p traps of the drain line. Make sure you have a decent slope on the drain line and keep them flushed. It helps if you start off with a clean evaporator or pan. Dirty coils create a menudo looking mess in the drain pan that will keep plugging your drain lines if it is not removed.

[thegrouse]

So the drain out side is the emergency drain?

Yes

[WhiplashTX]

There should be a float switch in your drain pan that shuts off the A/C when the drain gets clogged to prevent it from overflowing.

[oktx]

There should be a float switch in your drain pan that shuts off the A/C when the drain gets clogged to prevent it from overflowing.

I don't think we have this.

[oktx]

Can we pour a little draino down it?

[thegrouse]

Can we pour a little draino down it?

You would be better off with a shop-vac or compressed air.

[Olphart]

I don't have a float switch on ours either.

Your pan (under the a/c unit) collects water and if the primary drain clogs, your secondary drains to the outside and is connected to the pan. The primary drains (normally) into your sewer via normal pipes.

[bigbad243]

Look at all your sink, there will be a drain line coming into one of them. Get a bucket, pull that hose, clean it out, and look at all he **** that comes out of there. Then reconnect and you will be good.

[LFD2037]

There should be a float switch in your drain pan that shuts off the A/C when the drain gets clogged to prevent it from overflowing.

I installed AC's for a couple years & have never seen one of these.

[oktx]

Ok, went into the attic with a flashlight and an air hose. The inlet where we pour bleach into was holding water. I made a seal with my hand and blew air in it for about a minute. I looked into the inlet and the water was gone. There is no way to do that to the emergency drain as I can't get to it. I'm kinda afraid to blow it back the other direction.

[Smart]

Put your mouth over the drain tube and blow or suck....you Sooners should be good at that....

I have it happen once every 2-3 years. The bleach thing doesn't help much. Basically an algae/gunk/crud is building up in your drain pipe from the water draining into it and you need to unclog the primary drain. I plumbed in a ball valve where I can cut off the backflow in the drain and shoot a light shot of compressed air down the pipe to force the clog on down the pipe.....

If you have no place built in off the coil to blow compressed air or run a snake, you can turn off the AC, cut into you main drain line, do the air deal (and yes actually blowing with your mouth like on a straw will work as well if the clog is not too heavy) and then repair. Make sure you have pvc coupling ready for the repair.

[Smart]

Ok, went into the attic with a flashlight and an air hose. The inlet where we pour bleach into was holding water. I made a seal with my hand and blew air in it for about a minute. I looked into the inlet and the water was gone. There is no way to do that to the emergency drain as I can't get to it. I'm kinda afraid to blow it back the other direction.

See I told you you Sooners could do it..

If the emergency drain was leaking outside, there is no clog in the emergency drain and no reason to blow in it. Its fine and was doing its job..