My HVAC unit is constantly dripping water throughout the day. The dripping is coming from the PVC pipe that runs from the unit to a floor drain.

Just over a week ago, I went to change my 3-month filter and it was soaked. Water seemed to also have leaked out of the unit and pooled up on that metal duct area just to the right of the unit. A day after I put the new filter in, I checked it and it had a little bit of water on it, but now the filter is dry. However, there is still that constant dripping sound.

They want to charge $90 for someone to come out, so I am hoping there can be a DIY solution.

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  • 1
    Those red caps aren't exactly water tight. If you push down on that assembly, and it binds against the black insulation and becomes lower than where it goes into that open tee... it'll leak.
    – Mazura
    Aug 26, 2023 at 19:27

1 Answer 1


When the air conditioning is running, it both cools and dehumidifies the air in the home, so water condensing out of the air is normal and expected. That should be dripping into the drain pretty much all the time the A/C is on.

If the drain pan and pipe are not clear, water can back up rather than going down the drain. You may need to clean those.

In heating season, a high-efficiency furnace may also drip, but that will be water condensed from the exhaust gasses of the burnt fuel.

  • 2
    When I noticed the wet filter and water pooling up, I did clean that pipe with a brush tool they provided. There was a lot of lint and debris. The drain pan doesn't appear to be easily accessible without a tool to remove hex screws. If the filter is dry and there is no water pooling up, is it safe to say I cleaned it thoroughly enough with the brush?
    – flemming
    Aug 25, 2023 at 14:40
  • 3
    Probably that was enough, if the filter is no longer getting wet.
    – Ecnerwal
    Aug 25, 2023 at 14:46
  • 1
    This is related to one of the neatest concepts around cooling: the difference between latent heat and sensible heat. Oversized air conditioners do a bad job reducing latent heat and result in things feeling clammy. Undersized air conditioners will reduce the latent heat and do a great job dehumidifying but will result in a higher temperature because they don't capture all the sensible heat. Right-sized units will hit both targets.
    – KMJ
    Aug 25, 2023 at 15:50
  • 1
    @flemming It can also be the pipe going down into the floor clogging up somehow. They don't always go to the drain, and sometimes just poke outside where stuff like mud or bugs can get in there. Try pouring a bit of water down the T above the drain to test it. Aug 26, 2023 at 13:25
  • I once had a similar problem and removed the panel on the ductwork. Inside I found a dead mouse plugging the drain hole. Aug 26, 2023 at 14:41

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