I live in a condo with an in-home AC/heat pump. This morning we noticed that it was dripping water, and when we took off the front panel we could see standing water in the run-off tray. It was pretty clear that there was gunk (probably built-up dust) in the bottom of the tray, so we assume there's a bunch of it clogging the PVC piping too.

What is the best way to clean this out? We have one snake tool, but unfortunately it only reaches to about the top of the U-bend. I read that Drano is not a good idea, because without water pressure from above, it could sit in the U-bend and corrode the pipes. We poured about a cup of vinegar in this morning and are going to let that sit all day to see how it does. Is there anything else we can do if this doesn't work? We don't really want to have to call a plumber if it's just a clog job.

Update: All the vinegar drained through. Filled it again and it's a slow drain, though better than it was before. Hopefully a few runs of this will do the trick.

Here's some pictures to give you a better idea what I'm dealing with. The left shows the PVC piping. The right shows the coils, with the drainage tray underneath. The water pools underneath that lowest coil.


  • There are at least a couple dozen versions of this question on this site. Bleach is your best bet, but will work best if you can at least get a small flow started. Is the other end of the tube/pipe accessable? Once you get it unplugged remember to run bleach water down it every year.
    – Tyson
    Commented Jul 6, 2017 at 13:30
  • @Tyson No, it's not really accessible. It comes off of the unit, has a small U-bend, then goes straight into the wall. There's a screw connection to the unit itself, but it looks like it's glued on pretty well. We didn't want to attempt to remove it and then break it or not be able to get it back on.
    – David K
    Commented Jul 6, 2017 at 13:42
  • 1
    If you have access to the end of the discharge pipe use a wet vac to suck the stuff out of the pipe.
    – d.george
    Commented Jul 6, 2017 at 13:45
  • @d.george We did try that, and were able to get some of the standing water out of the tray. Unfortunately there's so much stuff in the way that it's impossible to get a good connection on the pipe itself. I can see if I can get a picture when I get home tonight.
    – David K
    Commented Jul 6, 2017 at 13:48
  • @Tyson Also, I imagine using bleach after we've used vinegar is a bad idea.
    – David K
    Commented Jul 6, 2017 at 14:01

1 Answer 1


The best solution to this problem is to install a drain system that allows for easy inspection and cleaning. Here is an example of "the right way" to plumb that:

Proper AC condensation drain

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