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Window Air Conditioner Leaking Water Into House – What To Check – How To Fix

Question: I just turned my window AC unit ON today and it is leaking water inside my house. What could be the problem? I had it running for 3 weeks and all of a sudden it started leaking. There is a puddle of water on the window ledge on the inside of the house. Water is on the plastic vent where the cold air blows out. I believe that is where it is leaking but not sure. Can you tell me how to fix this? My carpet is soaking wet, I need this to stop leaking, please help!

Window AC Leaking Water Into House - How To FixWindow AC Leaking Water Into House – How To Fix

ANSWER: You are going to check a few things to be sure the ac unit is installed properly and there is no water drainage block present
Unplug the window AC unit.
Clean up all the water on the AC unit, on the window ledge, and on the floor of your room.
Check and be sure the AC is tightly sealed in the window.
Do you feel warm air coming into the room around the AC unit?
If you feel warm air coming in you need to seal it correctly.
Seal in the window AC unit to prevent warm air from entering the room.
Check to see if the drain holes on the rear of the ac unit are blocked.
Clean the drain holes to allow water to drip out.
Make sure the filter is clean and not clogged with massive dirt or dust.
After cleaning up the water and having it turned off for 30 minutes or so, turn it back on and see if the water appears again.
If water appears and starts dripping into your room again, check to see if the AC unit is properly sealed in the window.
If the AC unit is not sealed correctly, the moisture in the air coming in from outside gets condensed by the cold air inside the unit and this extra moisture builds up in AC unit and then leaks.

Here are some other reasons water can drip from a window air conditioner unit:

If your window air conditioner is not sealed correctly, the warmer air from outside gets inside the air conditioner. When this happens, the moisture that is in the warmer air will be condensed by the colder air inside the air conditioner. When there is excess moisture inside the AC, water will leak. So if this is happening to you, make sure you have a good seal around the window AC.

There are drain holes (drip pan) at the rear of window AC units. They can get blocked from dusty conditions or dirt in the air. When this type of blockage happens, the water that would normally drip out will be trapped and water will leak from the front of the AC unit and at both sides of the unit. Be sure to keep the drain holes clean and free of debris. Also clean the filters or replace them to prevent any type of blockage that may cause a water leak.

Replacement Window AC Filters

Replacement Window AC Filters

If it is raining or there is heavy moisture in the air outside, water evaporates much less than usual. This leads to excess water moisture in the air conditioner and this will cause water leaks. This is normal for most window AC units and using a drip pan can solve the issue if there is heavy moisture in the air outside.

If the condenser pump in the AC is faulty or clogged, it will cause water to leak. You can check the condenser/pump if you feel confident. Check for any blockage or loose wires. If the pump seems to be okay visually, you will need to test the pump with a meter to see if it is faulty. If so, you may be better off buying a new AC unit.

How window AC unit works

Window AC – How It Works

Have questions about your leaking window AC unit? Please leave a comment below and we can assist.

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14 thoughts on “Window Air Conditioner Leaking Water Into House – What To Check – How To Fix”

  1. My mother’s air conditioner was holding water from a brief heavy rain storm today, she freaked out and told me to unplug it. The water resided on top where the window hold the unit. The unit needs adjustment or missing a gasket strip.

  2. Hi Douglas,
    I have a wall unit ac. I think the brand is Friedrich and its about 7-10 years old. When we have a nor’easter as we did last night water drips inside my house.
    Drips is the wrong word as it filled many baking pans of water over a few short hours.
    I had my condo association silicone caulk the unit as its on the second floor.
    My windows have recently been replaced so I know the water problem is not coming from the window.
    It’s the ac through deductive reasoning. I have no idea what to do next. The a/c works fine and I don’t remove it ever as its in a hole/case in the wall.
    How do I move forward? My property management says its my unit so its my problem.
    Who do I call for help?
    You sound like you know what you are talking about it. Do I just buy a new a/c? How can I tell if its the ac case? Sigh.

  3. Could turning the ac u it sideways cause any leaking, I discovered mine leaking last night quite a bit on a particularly humid day, so I was wondering if it was just the humidity or if I messed up by putting it in sideways

  4. Your advise about cleaning out external drain lines or holes in window A/C’s is largely obsolete.

    For some years almost all a/c’s have had “slinger” blades on the condenser fan that takes the internal water, slings it into the air and cools the condenser coil before the water/air mix goes outside. That way there is increased efficiency and no external water dripping.

    What typically happens to cause leakage is that an INTERNAL drain passageway that diverts water away from the bottom of the front evaporator coil clogs, preventing the water from reaching the rear condenser “slinger” fan. The only remedy is to take the cover off of the a/c and clean out that passageway, often an awkward process in terms of access.

  5. I live in an apartment my downstairs neighbor complained to the manager the matainace man drilled a hole under the ac and put a funnel under the hole, now my ac is leaking in my house. What should I do?

  6. My window unit started leaking recently and I haven’t been able to get it to stop… The first time around was an easy fix, and I leaned the unit farther backwards to allow the drip pan to drain easier… Eventually that stopped working. So I shoved some cotton into the pan and over the lip to wick away moisture. That worked for many months. Just had to change the cotton a few times. Finally, today was the day of reckoning… Woke up to a pool of water all over my bedroom. Spent the day sealing it and reseating it and sticking cotton in at every angle to no avail. Tomorrow I will pop it ope and clean it out. Where can I find the condensate drain line on a unit like this? Does it even have one? Once its dry and cleaned out I pray the problem is fixed… Otherwise its gonna be a sweaty winter here in the Philippines. Can you offer any more advice for things to check? How can I test the pump without a multimeter? I’d hate to pony up and buy one just to find out the unit is dead… Thanks for any assistance!

  7. About two and a half weeks ago, I noticed that water was leaking inside my apartment from my one and half year old air conditioner. I removed it from the window, removed the front piece and cleaned the fins and air vent with a heavy duty coil cleaner. I tried to remove the back portion of the unit but there was one unmovable screw so I had to make do with cleaning the unit from the front. I tried pulling some of the gunk in the back out through the holes but could only do so much without being able to take off the back piece. I let the unit dry and reinstalled, and was very careful to insulate the installation properly.

    The unit worked without leaking until last night. I had been hearing a kind of water stream sound, however, when it was on. And then of course I noticed the leaking again. Is there anything I can do to salvage this air conditioner? I do not have it on an angle out the window as I have read some conflicting advice and the unit seems very specifically designed, with its wings and everything, to sit at a right angle rather than downwards out the window. Would angling it somehow fix this issue? Also, there is a removable plug underneath the air conditioner but I understand that removing it reduces the energy efficiency of the unit and that then my electricity costs might go up. Is it worthwhile to just remove that plug?

    What would you suggest I do?
    Thank you,

  8. Our window units are not in the window, but placed in a cut out in the wall. It just started leaking on the right corner. My husband seems to think it’s condensation, and feels he needs to put some type of sheet metal underneath outside to catch the water.

  9. DIY Help & Repair Tips

    There may be excessive humidity in your area.
    Clean the drain line to be sure any excess water drains out instead of leaking in the room.
    Remember to unplug the AC before doing any checks or repairs.

  10. When I use my air conditioner the entire room gets wet, and damp. Not just around the ac. AC is a Friedrich only about 15 mos. old. Company/warranty Tech says nothing wrong with Air conditioner unit and that it’s working properly.

  11. DIY Help & Repair Tips

    If the AC is spraying or dripping water, the drain line is most likely clogged.
    Remove the panel and inspect the unit for where the condensation is drained out, clean the drain line to prevent water from coming into your room.
    There might be water in the bottom of the unit and this is leaking out into your room.

    What is the make and model number of your Window AC Unit?
    Let us know and we can direct you to what type of filter you need and where it is located on the AC unit.

  12. My window air conditioner is spraying water into the room and making a sound it hasn’t made before – as though it is working harder than normal. I will take your advice as to sealing it better, but I should probably change the filter. I looked at the diagram you provide but don’t see where the filter is. Any help is greatly appreciated.

  13. Patricia Hopkins

    Why my 4 years old air conditioning is running water inside of the house and still cooling

  14. Jessica Sanchez

    My a.c. unit is spraying about 4 drops every two seconds on the left side of the unit. It still cools very well but this issue has came up and my landlord tells me to move. I dont think it needs to be moved and if I was correct in saying this I believe the drain is clogged. I looked inside with the cover on and I saw water inside. Would this cause the spray of water and if yes can you walk me through the steps how to clean it? I don’t even know how to take it apart….please any help would be appreciated. Ty in advance

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