Symptom: My first AC drain line is overflowing - nearing the top of the trap sticking out of the top of the pvc pipe.

What I've Tried: It appears that the drain actually exits the home near the roof. (I live in a 2-story home. Is this common?) I have a Shop-Vac, but I can't reach where the outlet is coming out to attach the hose to it. So, I'm attempting to use an air compressor to blow out the pvc pipe from the pipe near the unit in my attic.

The current problem is that I'm trying to use a tire-pressure compressor (the kind that normally plugs into a car cigarette lighter) to do this, but the AC to DC power converter, to plug the device into my home outlet, is not doing the trick. A light comes on, on the device, but the compressor does not start up. It does start up when I plug it into my car's lighter outlet.

Questions:
1) Am I even remotely on the right track? This was based on my first thoughts/googling, then confirmed by a contractor I spoke with over the phone.
2) If I'm on the right track, is there a different kind of adapter I might need than the one I'm using, that will let me use this air compressor in the house? (The one I'm using: https://www.batteriesplus.com/productdetails/APT90311)

Thanks for any and all help!

 

Welcome to the forums.

In order to use that compressor in the house you need a 12v power source..... either a supply or a battery.

Typically the drain line you see up high is the secondary or overflow line.
There should be another line for the primary drain.

 

After looking at it some more, it seems like my 2 ac units' primary drain lines join together before exiting the attic. I still can't locate the exterior drain, but only one of those 2 drain lines is getting clogged, which tells me the stoppage must be in the small section of pipe before those 2 lines join. I haven't been able to unclog it manually, and hot water + dish soap didn't do the trick, just now. I guess my last resort option is just to cut that section of pcv pipe to clear the clog, or to replace that section of pipe, altogether.

I have seen a spot with 4 metal (copper?) pipes exiting the house, side by side. None of those appear to be dripping, at all, so I don't think that those are the drain lines. Maybe I'll find it, eventually!

 

The primary should end up in one of your bath rooms (under the sink).

 

I'll definitely take a look under the sink - I hadn't heard that, yet, and that would explain a lot!

What's the recommendation for trying to clear that clog, if I do manage to find it in a bathroom? Since it joins with another unit's pipe in the attic, I guess I'd have to plug those, in order for something like a shop-vac to work on the other end?

 

You may find the condensate drain line connected to an internal drain but that is not typically where it connects.

Cutting the PVC is the easiest way to access the line to make repairs.
You could install a cleanout trap there for future cleaning...... Trap