Asked on Jul 6, 2013

How do I un-clog a condensate pipe on my attic ac unit?

Sandra WhittierWoodbridge Environmental Tiptophouse.comMjordanlmj


The overflow pan for my ac unit in the attic was full, so I think the drain pipe is clogged.
12 answers
  • FloorNerd
    on Jul 7, 2013

    James, is the ac unit a regular box window unit or is it a central ac duck unit? Do you have a little pump attached to the side of the unit? Were is the drain line attached into.... Like main drain ect?....

  • Shirley R
    on Jul 8, 2013

    I have an older house and the shower/tub has three knobs. 1 is hot water and the 1 in the center changes the water from the tub to the shower and the other one is cold water. When I have the water on either tub or shower water is leaking out around the cold water knob! How can I fix this and what do you think it needs? The knob's are clear plastic with a silver piece in the center of each with Hot, Cold and the center one that turns the water from tub to shower has an arrow on it! Would love some feed back to stop this leak!!! Thanks, Shirley

  • Miles Enterprises Inc.
    on Jul 8, 2013

    ITsounds like you are describimg a delta faicet .shut off water to the house and replace the seats and springs in both handles

    • Shirley R
      on Aug 12, 2013

      @Miles Enterprises Inc. Thanks! I have to shut off the water to the whole house? You said to replace the seats? What is that? Do you mean washers? Their are little springs inside as well?

  • Plumbrite
    on Jul 8, 2013

    turn the unit off when you leave the house, when you get back hopefully the water will have drained down some and pour about a cup of bleach in the drain line. you can also try some compressed air, the blockages are usually soft, and the bleach will open up line in a couple of hours. If you have a pump make sure it is plugged in, and there is power to the unit.

  • J & J Refrigeration
    on Jul 8, 2013

    Use other contractors suggestions first. If they do not work. Use stiff but flexable strand of solid copper wire that is long enough for the entire drain tubing to clean out condensate drain, starting at where drain tubing is connected to a/c evaporative coil in the attic and working it to opposite end of drain tubing.

  • Mike Lee
    on Jul 8, 2013

    Most drain issues are caused by rust/dirt or algee in drain. So, to fix it first need to access why. Blow drain with /air tank at "T" or install one down about 8" away from coil. If you do not know how to do this, then it is best to call a professional HVAC service company. :)

  • Vincent Plumbing
    on Jul 8, 2013

    The clog is most likely at the trap. If it is draining slow - try pouring boiling hot water down the drain slowly. If it is totally clogged you can use an air compressor (make sure all the outlets are closed except the one you are blowing into and the one at the end). Give a shot of air - sometimes that works too.

  • Shop vacuum works wonders for this. One that can pick up water. Do not use a regular type. Also check the pipe along the entire length. If it dips up and down each dip acts like a trap. This often results in back ups as well. A plugged trap is a sign that you are not changing your filters as often as you should. While algae will build up, its the dust that is washed off the coil in the unit that causes most of these issues.

  • Mcguyvr
    on Jul 20, 2013

    Need to use wet/dry vac and vacuum line from outside, then add 2 cups bleach to drain pan. Afterwards pour one cup of bleach every 3 months to prevent future back-ups, or call a good service company to take care of your system.

  • Mjordanlmj
    on Jul 28, 2013

    After blowing out the line...I use a pool chlorine tablet in my pan every 3-4 months they work great

  • If your replacing your filter on a regular basis and your duct system is not leaking air into the return ducts after the filter mounting area. And the filter is tightly fitted with no bypass air going around it, then there is nothing else you need to do. Mold and sludge develops in traps because of dirt in the air. This collects on the fins of the cooling coil and as it falls down it travels into the drain line where it collects, much like the gunk that collects in the bathroom sink. It too from time to time needs to be cleaned. Putting any bleach or chemical tabs in the condensate pan can be dangerous to your health if fumes are created that enter into the air stream in the home. I suggest strongly unless you know how to rinse or clean traps and coil pans you should leave this to the pros.

  • Sandra Whittier
    on Jun 22, 2015

    They told me to use vinegar instead of bleach.

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