Portable AC Unit Leaking Water From Bottom? 10+ Culprits + Fixes

“My 10,000 BTU LG portable air conditioner is leaking water from the bottom. I have a puddle of water beneath the unit. Is this normal? Is something wrong with the LG portable AC unit? Do I have a clog? How can I fix this leakage?”

We received 2 of these ‘why is my portable AC leaking from the bottom’ questions. To help everybody with a leaking portable air conditioner inside, let’s break this down, shall we?

In short, it is not normal at all for a portable AC unit to drip water from the bottom. Unless it only leaks on rainy days (very high humidity levels), there is something wrong with your LG, Midea, Black and Decker, Frigidaire, etc. window AC unit.

portable ac unit leaking indoors
Portable AC units shouldn’t leak. Why they leak (and how to fix the leakage) depends on what type of drainage your unit has (3 types; we will cover each of them).

Here’s what you should immediately do if you see water coming from the bottom of a portable air conditioner to prevent further damage:

  • Shut it down. The unit is clearly malfunctioning, and running it can exacerbate the damage.
  • Soap up all the water. Portable air conditioners are leaking water inside the house. To protect your floor, carpets, and furniture, avoid potential electrical fire hazards, take a cloth, and soap up the water from beneath the unit.

Now, to diagnose the cause of the portable AC leakage, we will take a structured approach here. Every portable AC unit gathers water (works like a dehumidifier). There are these 3 types of portable AC units, based on how the accumulated water is drained (check which one you have):

  1. Drainage via condensate tank. We have a built-in tank that has to be routinely emptied manually. This usually means you have to carry the whole unit in the bathroom, and empty it by tilting it.
  2. Drainage automatically via an exhaust hose. These are known as ‘no drain portable air conditioners’. They might still have a condensate tank or drain hose, but the primary way how no drain portable AC units dispose of water is by blowing out humid hot air via the exhaust hose.
  3. Drainage via drain hose (with or without a condensation pump). All the accumulated water is channeled outdoors via a drain hose (hoisted through the window, next to the exhaust hose).  Some of these drain hose units can have a condensation pump to help pump to water against gravity up towards the window and then down on the outside of your home.

The causes for portable AC unit leaking water from the bottom depends heavily on which type of portable AC drainage you have. You can read more about these 3 ways of portable AC drainage here. Here are some examples of why a portable air conditioner of a specific type is leaking water from the bottom:

  1. Condensate tank portable AC is leaking simply because the tank is full. You need to slug the unit to the bathroom and empty the tank.
  2. Exhaust hose portable AC is usually leaking on rainy days. That’s when the humidity levels are through the roof, and the exhaust hose cannot remove all that water.
  3. Most common reason for drain hose portable AC leaking is a clogged hose. Remove the clog, and the unit should stop leaking water from the bottom.

Let’s list the most common reason for a portable AC leaking water for each of these types, starting with the condensate tank type:

5 Reasons Why Condensate Tank Portable AC Unit Leaks Water

In most cases, portable AC units leaking after from the bottom are condensate tank units. As mentioned, these are units with a built-in tank that collects water.

If that tank is full, or cracked, or the drainage to the tank is clogged, we will quickly see a puddle of water accumulating beneath the portable AC unit.

Here are the 5 most common culprits for condensate tank portable air conditioner leaking water (and fixed):

  1. Condensate tank is (simply) full. 6,000 BTU to 14,000 BTU units have between 1 and 3 gallon tanks. When the tank is full, you have to carry it to the bathroom, tilt them, and empty them. The tanks are not detachable; that’s why you have to take the whole unit with you to the bathroom. If you continue running the AC unit with a full tank, you will likely get a leakage since the water cannot go into the tank anymore.
  2. Cracked tank. If the tank is intact, it should collect the water. However, if you have a crack in the tank – due to wear and tear, carrying it to the bathroom so many times – the water will leak from that crack, and you will see that a portable AC unit is leaking water from the bottom. If you notice a crack, you should take water-resistant glue or tape and apply it to the crack to seal the tank again.
  3. Drain pipe to the tank is clogged. Portable AC units gather water in a drain pan, and channel that water to the tank via a drain pipe. If that drain pipe is clogged, the upstream drain pan will be full, and it will start leaking water down the portable AC unit, since it’s only relevant drainage method – via the drain pipe – is clogged. In this case, you should disable the unit, and knock the clog out with a piece of wire and flush the drain pipe with vinegar to prevent leakage.
  4. Drain pan is cracked. The drain pan, located deep within the unit, can be cracked. Its job is to collect the water and channel it to the condensate tank via the drain pipe. If, however, the drain pan (full of water) is cracked, that water will start leaking down the unit and on your floor.
  5. Defective float switch. When a tank is full, the portable AC unit can shut itself off. A float switch detects when the tank is full. If it malfunctions, the AC won’t be able to detect when to stop the AC and notify you that you should empty the condensate tank. How to fix a defective float switch? Well, in most cases, you won’t be able to. This is not something you can DIY; in most cases, you would throw such a unit away because the cost of HVAC technician coming and servicing the unit can cost a few $100, and for that kind of expense, you can get a brand new unit.

All in all, the condensate tank portable AC unit is mostly likely to leak. Let’s now have a look at causes of water leakage for automatic draining and drain hose portable AC units:

Automatical Draining Portable AC Unit Leaking (Exhaust Hose Drainage)

With these so called ‘no drain’ portable air conditioners the probability of leakage is very low.

Namely, these units don’t collect and dispose of water via a drain pan, drain hose, or condensate tank. They blow hot and humid air out of the back (via the exhaust hose), thereby automatically expelling water outdoors.

Now, the main reason why a no drain portable AC unit might be leaking is because it is being overwhelmed. Due to very high humidity levels, the exhaust hose is unable to eliminate all the water quickly enough.

This usually equates to this type of portable air conditioner leaking water on rainy days. During rainy days, the humidity is elevated, presenting a heavy drainage load for the exhaust hose to eliminate all the water on its own.

There is pretty much nothing wrong with a leaking portable AC unit; no damage or potential fixes you can do. It’s just a no drain portable AC unit that just doesn’t have enough drainage capacity, and it’s being overwhelmed. Getting a separate dehumidifier for these rainy days might be a good idea.

In most cases, these units have a smaller condensate tank as well. That also means that it has to have a drain pan and drain pipe, connecting to the said tank. This is it’s secondary method of removing excess water.

In limited cases, a no drain portable AC unit might be leaking because this tank is either full, cracked, or there is a clog in the drain pipe, and so on. If you suspect there is a tank-related issue, check all 5 reasons why a condensate tank might be leaking (mentioned above). Essentially, this smaller tank (secondary drainage) can have the same issues as big condensate tank units (primary drainage).

4 Culprits For Drainage Hose Portable AC Units Leaking On The Floor

Portable AC units that remove excess water via drainage hose or pipe have another set of reasons why it might leak. Namely, these units accumulate water in a drain pan, and remove it via the drain hose outdoors.

With some units, you only have the drain hose, and gravity does all the water pulling the water outside.

Other units will have a pump that actively pulls the water outside by creating enough water pressure for that water to be elevated above the portable AC unit and eliminates water outdoors. These portable AC units with pumps are usually used in the basement (working against gravity), where you usually have higher humidity levels as well.

There are a number of culprits that can cause a drainage hose portable air conditioner to leak water from the bottom. Here are the main culprits, with a short description of how to fix them:

  1. Clogged drain pipe. The #1 reason why this type of portable AC unit leaks is a cloggage in the drain pipe. The unit cannot dispose of water via the drain hose if that hose is clogged. If you have a clogged hose, you need to remove the clog. The simplest way is to use a longer wire to wriggle out the clog and vinegar to flush out the clog.
  2. Cracked drain pan. This is the case we covered above already.
  3. Non-pump hose is located above the unit. If you don’t have a pump, you have to take care that the end of the hose (usually flung out of the window) is below the portable AC unit. This is how gravity can help you eliminate water. If the end of the drain hose is located higher than the unit, the water will not be able to flow through to outdoors, and you will basically flood the portable AC unit.
  4. Pump problems. If the pump malfunctions, the portable AC unit will not be able to remove excess water via the drain hose. The result will be a portable air conditioner with pump leaking water from the bottom. In this case, you will have to fix the pump. That can cost quite a lot, and is many cases it makes sense to just get a new unit since the HVAC servicing costs for fixing a pump are quite high.

Here’s the short version of how to fix a portable air conditioner leaking water:

  1. Figure out which type of drainage your portable AC unit has.
  2. Diagnose with might be causing the drainage. That means checking the drain pan, drain hose, pumps, etc.
  3. Once you fix the culprit, the portable air conditioner should stop leaking immediately.

Hopefully, covering all these 3 types of portable AC units and culprits for leaking will help you fix your unit. Wish you all the luck. You can also check a similar article about window air conditioners leaking water inside (in many cases, it’s a bit easier to fix those).

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