11 Reasons Your Portable AC Fills with Water Too Quickly

Last Updated on January 1, 2024

Portable air conditioners generate water during the cooling process. This is due to the fact that portable ACs operate on the same refrigeration cycle as all the compressor-based air conditioners i.e. vapor compression cycle.

A portable AC filling with water too quickly is a real problem. It is very uncomfortable to drain the condensate pan every few hours. Especially at night when you need a good consistent sleep after a long day of work.

The primary reason why your portable AC fills too quickly is high humidity. This could be seasonal or specific to the region where you live. However, many times internal problems like dirty filters, clogged coils and airflow limitation can also cause your unit’s condensate pan to fill unusually fast.

Actually, clogged filters and evaporator coils, or anything blocking the path of air through your portable AC unit, leads to ice that melts and keeps filling the water container continuously.

Many portable air conditioners have self-evaporation technology. This means that water produced is automatically exhausted through the exhaust hose. However, all portable ACs do not have this technology.

Even if your portable AC can automatically expel water, most of the ACs are partially evaporative. Which means they still have a water tray. The purpose of the water tray is to hold water in case it is not expelled at the same rate as it is generated.

Portable AC Vented Through Window

Why Is Your Portable AC Filling with Water Quickly

1. High Humidity in Your Area

Your portable AC is generating water, whether less or more, by the condensation of humidity from the air.

The amount of water that it generates is in direct proportion to the humidity in the air.

If you live in an area with high humidity, more water will accumulate in the condensate pan of your portable AC.

For example, in Louisiana or Texas, the average relative humidity is about 75 percent. This is really high, and they are among the top humid cities in America.

Condensation on Glass

So if you are living in one of these regions of US or any other comparable regions in the world, you will have to empty water pan pretty many times.

In cities with low humidity, like Nevada or Arizona, that have a very low average relative humidity (below 40 percent), the frequency of manual drainage is very low.

Most of the portable ACs are partially evaporative and in these cities, you may never have to care about condensate. The reason is the automatic exhaust of most of the moisture that is accumulated.


In case you are thinking of buying a portable AC, consider which type is best for you.

In highly humid regions, it is best that you use a partially evaporative or fully evaporative portable AC to avoid continuous interruption and inconvenience.

However, in a region with low humidity, you may use a portable AC without self-evaporative technology, as you will not face problems with recurring drainage.

The second option would be to use a condensate pump that will automatically remove excess water by itself. You can know more about that here in this article.

2. Dirty Air Filter of Portable AC

Dirty AC Filter

The air that is cooled by your portable AC is delivered to the living space after it has gone through an air filter. Filter blocks dust and debris from the air.

Your portable AC filter has to be cleaned after specific hours of cooling operation. This duration depends on the quality of air that passes through it.

One of the causes why your portable AC keeps filling up is a dirty filter.

A clogged filter in your portable air conditioner reduces airflow, causing the evaporator coils to freeze and moisture to drip into the condensate pan.

Even if you have a partially evaporative portable air conditioner, water will not be exhausted at the same rate at which it is dripping and you will have to keep emptying your portable AC.

Most of the air conditioners have filter reset indicator. It turns on when the filter is dirty or specific number of hours have been passed in the operation.

The duration after which the filter reset light turns on is assigned by the company. Portable air conditioner will not turn ON until you take out the filter, clean it and then put it back on.


Give a check to air filter of your portable AC. Extract the filter out and clean it. The filters in air conditioners are almost always reusable, so you will not have to change them.

Use lukewarm water to wash the air filter gently. Allow it to dry properly before inserting it back.

Here’s a simple video demonstrating how to clean your portable AC filters

3. Just a Humid Season

Generally, relative humidity is variable in different cities and regions of the country. However, it also depends on the season in which you are operating your portable air conditioner.

On certain days of the year, humidity levels are higher than others, which may result in a relatively greater amount of water vapor. This could be a seasonal occurrence.

The times of the year when the humidity is maximum and minimum vary according to the state and city you are in.

For example, in New York, September is the most humid month and the least humid is April.

This means that around September your portable AC will generate more water compared to April. While in Nome July is the most humid month.

Useful Observation: If all of a sudden, your portable AC is accumulating a large amount of water, it is probably not due to seasonal change.

The reason is that the effect on humidity in the air by the weather is not impulsive. And the variation in increase and decrease is not massive.

So if you encounter large amount of water generated by your portable AC on a specific day, it is probably due to some other problem.

4. You Just Bought The Portable AC

If you have purchased a new portable AC and it is generating a lot of water then it is very rare that it has a technical fault.

The reason is air conditioner companies are very keen of their reputation when selling the unit. They cannot afford to hurt their reputation as there is so much competition.

Package With Appliance Inside

Unless the damage or problem in the AC is during delivery, you can return the portable AC to get a new one.

The reason of course primarily may be high relative humidity in the area you live but it might just be because you have bought a new unit.

When you air condition your living space after a long time, or the first time, AC removes the humidity from the floor, walls, ceiling, furniture, and other things including the air. This might result in a high amount of water accumulation by your portable AC.


If your new portable AC keeps filling up give it some time before simply returning it.

In case the problem persists then your AC might be faulty, or it is not suitable for the area you live in i.e. high average relative humidity.

If it keeps filling up due to high humidity, you might want to consider a partially evaporative or fully evaporative portable AC. Or you could get a condensate pump installed on it.

5. Faulty Condensate Pump

An easy way to get rid of this repeated inconvenience of emptying your portable AC water tank is to set up a condensate pump.

This water that collects in the water pan will automatically be directed to your desired location. Plus, It is very easy to set it up.

If the water tank keeps filling up even with a condensate pump, there may be a problem with the condensate pump setup.

Either the condensate pump is faulty, or the drain hose entering or leaving the pump is blocked or bent. This is stopping the route of water.


It is a good idea to check the pipe running before and after the condensate pump before replacing it.

If you have not used a condensate pump till now, give it a look, especially if you are bothered with draining your portable AC again and again.

It is very easy to set up. All you have to do is attach the drain hose to your AC and connect it to the condensate pump.

The condensate pump is connected to an electricity source. The water keeps collecting in your condensate pump until it has reached a certain level. When that level is reached, the pump will start by itself and water will be directed to your desired location.

Here’s how condensate pump removes water automatically

You may run the drain hose directly into another location and drain water without using a condensate pump.

However, keep in mind that it needs gravity to do so. So if the water has to travel against gravity (upward direction) this method will not work. In the condensate pump, this problem is resolved and water may be pumped to another location against gravity.

The most convenient option thereby is using a condensate pump. If you want to go with it, I picked one for you. Click here to see specifications.

6. Water Not Draining Properly

The most basic way of draining water from your portable AC is to manually drain it. For that, you will have to remove the drain plug and allow the unit to drain into an empty container.

How often you will have to do it depends on your humidity and how long you run your portable AC. It may vary from 6-8 hours to several weeks.

If you are draining manually by this basic method, you will know in case there is a problem. For example, if your AC indicates that its water tank is full, but no water comes out after you remove the drain plug.

One of the reasons for this may be that the water is blocked from coming out of the water tank due to a clogged drain. There is nothing that would clog it from the inside, so something has probably gone from the outside when it was not covered.

If you are using a drain hose to automatically remove water from your portable AC by gravity method or condensate pump, your water tank should never fill up.

If water continues to accumulate in the condensate pan, it may be due to a blockage in the drain hose.


Check for the bends in the drain hose, especially 90-degree bends. Also check the pipe after the condensate pump, in case you are using one.

This is how you can attach drain hose with your portable AC to constantly remove water from it. So you never have to empty it. This will only work if water goes in the direction of gravity.

7. Defective Portable AC Blower Fan

A consistent flow of air through your portable AC fan is important for its proper functioning.

A faulty fan, that is either not running at the required RPM, or not running at all, will lead to frosting of evaporator coils. When this ice melts, it will fill your portable AC very quickly.

Let me explain why…

Actually, reduced airflow, due to improper functioning of the fan, does not allow enough air through the unit. This prevents taking enough cooling away from the evaporator coils.

As a result, ice develops on coils and portable AC compressor may stop functioning for a while, until ice melts. As this ice melts, condensate pan will fill with water quickly.

During this time, ice will melt slowly with a low-speed fan. After melting, a faulty fan will result in refreezing of evaporator coils when the compressor restarts.

This process will repeat, preventing your AC from completing its cycle.

AC Blower Fan

What Causes Inadequate Blower Fan Operation?

  1. Give a look at portable AC blower fan blades. If they are damaged, even with adequate RPM, the airflow rate will become low. If that’s the case, you will need to get the fan replaced by the exact model.
  2. Fan Motor can be a culprit for incorrect fan RPM. Low RPM causes less air to flow through the unit. Motor will need to be checked for shortages, continuation, and other faults. You can get it repaired if the fault is minuscule. Otherwise, I advise you to get a new one, it will save you a lot of time and trouble.
  3. There is also a possibility of other electronic components causing incorrect fan operation like switch, relay, control board etc. After diagnosis, they will need to be replaced by exact same model and type.

Note: If you do not have experience with diagnosing electronic components like motors, circuits, circuit components, etc., I highly recommend you get it checked by a certified technician.

If that is the case, the only thing you should do is to look for faults that are prominent and noticeable. Your life is more important than anything.

8. Clogged Evaporator Coils

Your portable AC unit has heating as well as cooling coils.

Heating coils are also called condenser coils.

Cooling coils are also called evaporator coils.

Air is cooled when it passes through the evaporator coils of the unit. Water is also condensed from the air by these coils as a secondary operation.

Both the condenser and evaporator coils of a portable AC must be clean for proper airflow. If the portable AC fills up too quickly, the evaporator coils are likely the source of the problem.

Let me elaborate…

Clogged portable AC coils allow less air to pass through them. Consequently, airflow rate is reduced than required.

As I said earlier, required airflow needs to be maintained through evaporator coils. If airflow is less than required, ice will develop that will melt continuously and fill up water tray repeatedly.


You need to keep your coils clean, just like you keep your filters clean.

The coils of portable ACs will get dirty over time, but they won’t require cleaning as often as filters.

Clean debris and dirt carefully, with a suitable brush, in a gentle upward and downward motion. Then you could either use a solution like warm water and detergent or dishwasher liquid to clean your portable AC coils.

Video demonstrating cleaning of portable AC refrigerant coils

9. Less Condensate Pan Capacity

One of the reasons why your portable AC condensate pan or water tray fills very quickly may be its small capacity.

A small-sized condensate pan will fill up quicker than that of a larger size and you will need to empty it more often.

There may be other issues in addition to a small condensate pan that are causing your portable AC to require frequent emptying, leading to discomfort.

For example, let’s say, for some reason(s), whether they be dirty filters, clogged coils, faulty fans, etc. your portable AC coils are icing up.

Ice will melt and quickly fill up the condensate pan. You will have to empty it frequently.

On top of that, a small capacity condensate pan will add to the problem of an already high rate of water moving into it, due to icing. It will fill even quicker and you will have to empty it even more often.

Therefore, I would advise you to first check for other problems discussed in this article, before concluding that the culprit is less water holding capacity of your portable AC.


You can always use a drain hose to get rid of water automatically by bypassing the condensate pan.

If you need to remove water from your unit at a height, a condensate pump will solve the issue permanently. You will never have to manually empty your unit’s condensate pan again.

You can click here to view the specifications of my preferred condensate pump.

10. Extreme Humidity in Room of Portable AC

Very high relative humidity in the room where your portable AC is running could cause it to fill frequently.


In this case, there are two scenarios after which your portable AC is accumulating water at a very high rate:

  1. You shifted your portable AC from one room to another and now it fills up too frequently.
  2. You are running your unit in the same spot but now the number of times you have to drain water has increased.

In the first scenario, it is very obvious that relative humidity in the new location of your portable AC has increased a lot.

This increase may be due to working in humid areas of your home, such as the laundry room, kitchen, basement, or attic, or defects such as poor insulation, cracked foundations, or water pipe leaks.

In the second scenario, the reason is most likely within the unit like a blocked filter, faulty components, clogged coils, etc.

If there is no internal fault, then relative humidity around portable AC is severely increased which can be due to the defects mentioned above or seasonality, or both.


Here’s a simplified version of the steps to diagnose and fix: (scenario 2)

  1. Check for reasons for very high water accumulation within your unit mentioned in the article.
  2. After going through that, check the room, in which you are running portable AC, for any faults like leaking pipes, inadequate ventilation, and water leakage through the structure.
  3. If the first two are not the source, use either a gravity method for drainage by vent hose, or condensate pump in case you have to take water against the gravity, to completely get rid of manual draining.

11. Malfunctioning Water Level Indicator

Several other components are directly or indirectly involved in the condensation process of your portable AC.

Wet switch, float switch, and water level indicator are all names of one apparatus. It is responsible for identifying the true water level in your portable AC’s water tank.

A faulty or misplaced wet or float switch in your portable AC can give an incorrect signal to the unit about the water level, causing it to turn off sooner than expected. As a result, you may have to empty it before it’s filled to the maximum capacity.


Diagnosis for wrong water level indication is easy.

  • When the portable AC unit indicates it is full, check its water level at that time.
  • Note this water level.
  • Do this a couple of times.
  • If your portable AC’s water tank is not full after multiple checks, its water level indicator may be the cause.
  • Then you can replace the float switch with a new one that is of the same specifications.

How Often Should You Drain Your Portable AC?

Water Spilled on Floor

The frequency of drainage of your portable AC in a day depends on various factors. It depends on humidity, number of hours of operation, and the type of portable AC you have.

If you have an air conditioner that has self-evaporative technology then most of the humidity will automatically be removed through the vent during the exhaust of warm air.

Most of the portable ACs in the market have self-evaporation technology. There are further two classifications of the portable AC though: Partially Evaporative Portable AC and Fully Evaporative Portable AC.

Most of the portable ACs are partially evaporative. So if you have just bought a portable AC and you don’t which one it is, most probably it is partially evaporative.

Partially Evaporative Portable AC

Most of the portable ACs available in the market are partially evaporative ACs. They have self-evaporation technology.

However, they will not exhaust all the humidity that is collected during the cooling process. They have to be drained periodically, depending on the humidity in the air, unless there is one of the other problems stated above.

Fully Evaporative Portable AC

Fully Evaporative Portable AC is completely autonomous in removing the humidity from the air. If you want to completely get rid of the hassle go with this one.

Wrapping up…

So in short there are various reasons why your portable AC fills relatively quickly. Relative humidity is the primary reason for a faster accumulation of water.

However, several factors can be controlled, such as dirty filters, faulty condensate pumps, and clogged coils. Check these factors in case humidity is not the issue.

Also, select the portable AC carefully depending on the climate of the region you live in.

If humidity is very high, and your portable AC is not doing a very good job at exhausting, consider modifications like draining through a hose via gravity or a condensate pump.

2 thoughts on “11 Reasons Your Portable AC Fills with Water Too Quickly”

  1. Rosemary Ariffin

    HI I live in the Tropics where it is very humid 80%. Recently, last week to be exact I have been having issue with my portable AC. It keeps on indicating the excess water tank is full and I have to discharge water every 30 minutes. This had never happened before since purchased in April 2020. I clean air fliters every 2 weeks, and now the air filter is very clean but still have water discahrged excessively. So I find it unusual. If you have a solution do let me know.

    1. Rosemary Ariffin I assume that you have partially evaporative portable AC as most of the portable ACs in the market are of this kind. Well first of all it is abnormal this is not supposed to happen. Considering that water starts collecting so quickly I think you may have clogged evaporator coil or flow of air is less or blocked in some way. This in turn generates ice and keeps filling the container.
      Your portable AC is relatively new it is good idea to seek customer support primarily.
      If however nothing resolves the problem you can use an external accessory like drain hose and/or condensate pump to permenantly resolve the problem.

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