Portable AC Filling Up With Water Quickly? Here’s What to Do

Is your portable air conditioner filling up with water quickly? It usually happens due to one of the following:

  • High humidity air in your home or outside
  • Dirty air filter inside the portable air conditioner
  • Clogged drain holes inside the portable air conditioner
  • Clogged drain line connected to the portable air conditioner
  • Broken condensate pump connected to the portable air conditioner

In this article, I’ll explain what you need to do when your portable air conditioner fills up with water quickly. I’ll also provide some helpful maintenance tips so your portable air conditioner doesn’t fill up with water quickly again.


Why does a portable air conditioner fill up with water?

A portable air conditioner fills up with water due to high humidity, a dirty air filter, clogged drain holes, a clogged condensate drain line, or a broken condensate pump.


High humidity air in home

If you have high humidity in your home’s air, then your portable air conditioner will collect more water.

The reason is simple—humidity is a measure of the amount of moisture in the air. More moisture in the air means that your air conditioner will collect more water.

It’s like wringing out a soaking wet towel when compared to a slightly damp towel—a lot more water comes out of the soaking wet towel.

Your portable AC probably won’t collect much water when the humidity is low. In fact, most portable ACs nowadays blow out moisture through the exhaust hose. So there’s a good chance that your portable AC won’t collect any moisture at all.

But when the humidity is high, your portable AC will definitely collect some water. Don’t worry! This is a normal thing. You’ll just need to empty the collection tank regularly.

Water draining from portable AC condensate tank
Emptying the collection tank on a portable AC

Dirty air filter

It may sound counterintuitive, but a dirty air filter will cause a portable air conditioner to fill up with water. Why is that? It’s all due to airflow.

A dirty air filter reduces the airflow through your portable AC. When this happens, the air going through the AC gets much colder, and more condensation builds up. This causes the collection tank to fill up much more quickly.

Another thing to look out for is a frozen coil. The low airflow caused by a dirty filter makes your AC’s coil more prone to ice buildup.

When your coil gets frozen, the ice melts and the collection tank fills up quickly. Most times, an overflowing collection tank is caused by a frozen coil.

To prevent this from happening, clean the portable AC’s air filter at least once a month.

Most portable ACs have a reusable mesh filter that can be sprayed with water to remove the dust. Allow the filter to dry completely before reinstalling it into the AC.

Portable AC - Filter
A slightly dirty air filter in a portable air conditioner

Clogged drain holes

Depending on the model of your portable AC, there may be one or more drain holes. The drain holes can be either inside or outside of the AC. Some drain holes let the moisture flow from the coil to the collection tank, while others let the moisture flow out of the unit from the collection tank.

These drain holes are prone to becoming clogged by either dirt, dust, or slime. The longer you run your portable AC, the greater chance that one of the holes gets clogged up.

Unclogging a drain hole is not too difficult, most times you can unclog it using a brush. For more stubborn clogs, you can suck out the debris using a wet/dry vacuum.

While you’re inside the AC unit cleaning the collection tank and holes, it’s a good idea to use some bleach to sanitize the collection tank. Sanitizing the tank with bleach helps to prevent slime growth in the future, so there will be fewer chances that the drain gets clogged again.


Clogged condensate drain line

Most portable ACs have an option where you can connect an external drain line to them. The external drain line allows you to continuously empty its tank so you don’t need to manually empty it.

Eventually, the drain line can get clogged from dirt, mineral buildup, or slime growth. If the drain line is clogged, the water won’t be able to drain and ends up backfilling into the portable AC.

To unclog the condensate drain line, first, disconnect the drain hose. Next, use a brush to clear out the clogs from the hose. If the clogs are stuck inside of the hose, use a wet/dry vacuum to suck or blow the clog out.


Broken condensate pump

If you have a condensate pump and an external drain line setup with your portable AC, then that may be the issue.

The condensate pump is required to pump water out of the portable AC to drain, usually outside somewhere.

If the condensate pump breaks, then it won’t be able to pump out water from your AC, and your AC’s tank may overfill.

If the condensate pump is broken, in most cases you should just replace it. They are usually cheap enough that replacing them won’t break the bank.

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