Long story short, a/c repair guy fixed my a/c system in my attic today, it had shut off due to a moisture warning in the pan because of a clogged drain. Fixed the drain, installed a new moisture sensor, told me to check the pan over the next couple days to make sure the water level goes down.

  • should they have vacuumed the water out of the pan... it's nearly full.

  • should I vacuum the water out of the pan?

  • the PVC drain pipe leads to the unit, not the pan. How will it drain? Did they guy just mean it would evaporate? I'm in GA and the humidity is 100% this week...stuff doesn't evaporate that fast around here...though it is in an attic in the middle of July.

Any thoughts or ideas on next steps?

  • A good tech would have removed the water somehow.
    – RMDman
    Jul 5 at 22:04

2 Answers 2


Do you need to remove that standing water from the pan, or should the service tech have done it? Strictly speaking, the answer is 'no' to both, but neither is a bad idea. Yes the water would eventually evaporate out of that catch pan but you're right that this could take a while. It would have been a sign of thoroughness for the tech to have removed the water. At this point in the season it may be that he has such a long list of service calls to complete that there's no time for doing anything that's optional.

International Residential Code (which I'm assuming would be applicable to your location in Georgia, USA) makes some requirements about condensate drains. See IRC 2015 M1411.3.

Part M1411.3.1 requires secondary protection where damage to building components would occur as a result of overflow of the primary condensate collection system. This stuff is normally applicable for an air conditioner located in an attic. The Code offers the choice of four options:

  • auxiliary drain pan with separate drain
  • secondary drain line attached to the equipment built-in drain pan
  • auxiliary drain pan without a drain, but with a water level detection that can shut down the equipment prior to overflow
  • water level detection that will shut down the equipment if the primary drain is blocked

It sounds like your system is installed as a hybrid between the third and fourth options.

That said, water damage is a big deal and a belt-and-suspenders approach to prevention is prudent. While the water sensor saved the day this time, you might consider it worthwhile to revamp things so that the secondary drain pan actually does drain away rather than merely holding water.


If the drain is working, there should be no water in the drain pan.

To remove potential mold build up in the drain pipe, pour some bleach and let it sit for a while.

The drain should be working after that.

The fact that it shut off says the water level sensor was working and did not need replacement.

The PVC drain pipe should go under the drain pan.

  • From what it looks like, the drain line runs only to the AC unit itself, not the emergency drain pan. The pan itself is full of water with no where to go it seems. Jul 5 at 22:46
  • 1
    @AlA.Batman that would be not correct, the drain pan must have drain pipe (1/2 inch size), it is not emergency, it is normal humidity collection. It could drain up to 3 gallos per day or more.
    – asinine
    Jul 5 at 22:49
  • 3
    Pans should be empty. If it's not, the drain is still plugged. Edit: unless it's an emergency pan under the whole unit or something like that, I suppose. But not emptying that is lazy on the tech's part.
    – KMJ
    Jul 5 at 22:52
  • The drain could be plugged—or the pipe may be backpitched. @AlA.Batman, can you provide pics?
    – Huesmann
    Jul 6 at 13:16
  • @Huesmann from what I can see, there is no drain in the pan. This is an emergency pan underneath the entire unit...there is a small pVC pipe leading out of the pan, but it is only 3" long and is capped, so doesn't actually drain anywhere....|... I called the tech back and apparently they don't remove water because of possible liability if it damages the ceiling from spilling or flooding, that seems ridiculous as I thought they should fix the problem to begin with. I'm using a solo cup and a mop bucket to try and get as much water out as possible. Jul 6 at 14:32

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