During the summer when it gets 90+ degrees outside my ac creates a lot of drainage from the attic. The drain line was made to just drip onto the garage floor by the homebuilder. Well the water, especially on 90+ days, is splashing onto the drywall. There were a couple mold spots I treated with bleach and now have plexiglass in front of..

Is this a normal installation? What's the best way to fix this issue because my current set up obviously isn't a good long term fix. I'm a complete newbie so I apologize for my ignorance about this.

Thanks so much.

drain water splash location

drain from ceiling shown with proximity to wall shown

hvac attic setup

  • 3
    I have never seen even a secondary drain set up to deliver water on the garage floor. The good side is that you see it right away. This must be a secondary drain and the primary is clogged. Of course if the builder put the secondary there, then one wonders . . . Rather than a plexiglass shield I would attach a length of flexible clear tubing to the ceiling tube and hang it in a bucket. Jun 28, 2018 at 10:48
  • 2
    What a horrible idea, having the water drip onto the inside floor of a garage! Jun 28, 2018 at 12:14

3 Answers 3


An AC unit will produce condensate all the time, not just when its over a certain temp outside.

Check your AC Unit in the attic. The Primary AC condensate drain is normally drained to either the main house drain or to the outside via a PVC pipe about the same size as the on draining into the garage.

There is a secondary drain, think an emergency notification that the Primary Drain is clogged. or not working. The drain you are seeing in the garage is most likely hooked to the drip pan hanging under the AC unit to catch any leaks not handled by the main drain, or the AC Air Handler sweating in the heat of the attic. In most areas the drip pan is supposed to be an electrical float system to shut off the AC unit is there is too much condensate in it, as that means there is something going on with the AC unit.

Use the attic access in the garage right next the drain pipe and see if that is the drain attached to the Air Handler itself or the emergency drain attached to the drip pan.

If you see another PVC pipe connected to the Air Handler itself, follow it in the attic to see where it goes. If it leads outside, it normally will be draining somewhere near the AC Compressor outside, but might be somewhere else. If you find it outside, a quick fix is to clear it out using a wet vac.

Long and short Pics of the AC unit in the attic will help diagnose the issues, but most certainly a call to the AC Service Company is most likely a good thing if they have not been out to Service the AC system this year!

  • 1
    Thanks so much for your reply! You're correct, the pipe going onto the garage floor is from the drip pain. Two of the pipes from the ac are going into the drip pan, the third goes into the water heater closet, and down a drain in that room. The drain has no visible water in it. I can't find any pvc pipe around the ac compressor outside or anywhere around my house. Does my added picture help show where my problem might be? (it was actually 3 photos that I made into 1 photo, hence the angle changes)
    – Eric
    Jun 28, 2018 at 20:00
  • Photos were just as I suspected. Where it is resting in the drain by the water heater, there might be enough play in the pipe to pull it up 3 or 4 inches (enough to hook a shop Vac(wet Vac) onto it. This should suck any clogs from the pipe ... if they are too bad. This should be done one or twice a year...or so. If your shop vac hose is larger than the pipe end. kind of block off the difference with something....your hand a rag, Duct tape.. Jun 28, 2018 at 22:23

Seems to me that when the AC is running the water should be draining through the pipe that is going into the water heater closet. If there's no water going through that pipe then most likely it's plugged. Is there an access panel so you can see from the inside and see if water is draining into the two pvc drain pipes. If not I would cut the drain pipe that goes to the closet near the AC unit and see if water runs out. My guess it will because the plugged up area is most likely where the multiple 90 degree fittings are. The good part is it's pvc so as long as you cut it in the middle of a straight section it's real easy to glue it back together. It looks like they tried to make a trap, and someone correct me if I'm wrong, but I don't think you need one since that closet drain is open.


Without being able to inspect the installation, it's difficult to say for sure, but here's my $0.02. The main condensate drain is not plumbed properly, which causes it to drain slowly. When the unit is producing more than average condensate, the main drain is overwhelmed. This causes condensate to use the secondary drain, which drains into the drip pan.

If this problem just started (didn't happen before in similar situations), then it's possible that the main drain is clogged/restricted. If that's the case, you'll want to clean/clear the main drain.

If this is not a new problem, you might want to consider fixing the main drain.

The other possibility, is that the unit is simply sweating due to high humidity. If this is the case, then you'll have to manage the water coming from the drip pan more effectively. This could as simple as extending the pipe, and having it drain in a more convenient location.

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