Top Reasons Why a Portable Air Conditioner Fills with Water Quickly

A well-maintain air conditioner can keep your home at your desired temperature for as long as you own the home.

While most people only consider changing the air filter, they quickly notice that HVAC maintenance requires much more work. These units collect water as well. 

While most prevalent in portable units, all air conditioners can quickly fill with water. The reasons for this water build-up vary from one model to the next, but they all fall under 2 categories. The water can come from the air in your room or as the byproduct of debris collecting inside the conditioner. 

While both reasons can create a mess of your room and your portable HVAC unit, there are easy fixes for them. However, you must use the right procedure for your situation.   

The Top Portable Air Conditioner Pan Water Buildup Causes

A well-maintain air conditioner is a marvelous invention. With a few button clicks or a turn of a dial, you can have your room as hot or cold as you want it.

These machines make modern living possible. Portable units take things to the next level as you can easily move them to where you need them. 

While most people understand they need to properly maintain their portable air conditioner, they might be left confused when they see water collecting inside the device. The problem is that the source of the water is usually difficult to spot. 

Luckily, most portable water built up comes from two specific sources:

  • Highly humid air
  • Leaks and clogs in the condenser line

How Dangerous is Water?

Fortunately, water build-up is not a common problem for most portable air conditioners.

Modern portable units come with built-in self-evaporation systems that keep them dry. These systems vent the leftover cooling moisture through the exhaust hose. Cleaning the vents is usually the only maintenance they need. 

However, older models do require routine emptying every few hours. While some models will shut off automatically when the water reaches a threshold, you must remove the moisture manually.

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If left alone, these units are prone to overflowing which can ruin your floor and furniture among other issues. 

Regardless, a little water will not hurt your air conditioner. It is a normal occurrence in most cases, and it does not become an issue until the water pan overflows.

Either way, you can prevent or reduce the leakage if you do the right fix for your unit’s particular cause. 

High Humidity Draws the Moisture from the Air

Most of the moisture that collects inside your air conditioner comes from the air it is trying to cool. Air conditioners use a coolant to transfer the heat inside your home to the outside, cooling your home in the process. 

As the fans push the hot air through the unit, the moisture in the air will condense on the cold coolant tubes before dripping into the collector pan.

It is the same process by which water collects on the outside of a cold glass. The water should flow out through the condensate line if one is present. 

The effect gets amplified when the air is humid. Humid air holds more moisture which just aggravates the whole situation. 

The Condition is Worse When Taking the Unit Out of Storage

The effects of high humidity are compounded by long storage with the air conditioner off. Throughout winter, or through the normal shipping and handling for a new unit, water can condense out of the air and settle into the condenser lines. 

With the conditioner off, there is nothing to remove the water from the system until you plug it in and turn on the power. Then, the water flows out of the system until the air conditioner can stabilize the air and coolant flow through it. 

Dehumidify the Room to Stop the Water 

Because it is a natural phenomenon, there is nothing you can do to prevent moisture build-up from humid air. Luckily, the water will not do much, letting you ride it out until the air conditioner cools down the room.

Most portable air conditioners come with built-in dehumidifiers for just this reason. 

If you want to help your HVAC along, you can dehumidify the room before you turn it on.

That means closing windows and doors to reduce the space the air conditioner must cool down. You can even run a separate dehumidifier as well. 

A Clogged Air Conditioner May Leak

Water can start collecting in your air conditioner’s pan if the condensate line is either clogged or has leaks.

The two conditions are often linked and usually the result of the same problem. Dirt, hair, or mold can seep inside the machine to block the tubes or the evaporator. 

Both problems derive from slightly different reasons. The evaporator is connected to the outside through the air vents.

Therefore, it is vulnerable to any debris brought inside via wind or by the normal airflow through the unit. 

A Condenser Clog Can Raise Humidity Levels and More Moisture

As the blockage grows, the evaporator will function properly leading to higher humidity levels. The extra moisture will drip into the pan creating the perfect breeding ground for algae in the pan and the lines leading to it. 

Even if you cleaned out the evaporator, the condensate lines can still clog up if you do not flush them before starting them after long storage. Algae, slime, and other pests can get into the empty lines, retaining more water while releasing a musky smell.  

In either situation, the debris can block the flow of the condensate, causing it to pool and freeze in place. As the coolant melts, the pressure in the lines can crack the pipes to let more moisture and condensate to leak out. 

Proper Maintenance will Slow the Process 

Once the condenser lines break, there is no way to fix the air conditioner. Therefore, your job as the owner is to keep that from happening.

Luckily, regular maintenance should keep the damage to a minimum. 

  • The best thing you can do for your air conditioner is to clean the filter. A clean filter keeps the debris from reaching the evaporator. Most manufacturers recommend changing the filter every 30 to 90 days.
  • Pets, smoking, and dirty environments require more work. If you smoke or have pets, you may want to clean out the filter more often. This is especially true during a dry season. As a professional HVAC technician if you need help devising a maintenance schedule.
  • Call a professional HVAC technician to give your air conditioner a full cleaning. A professional HVAC company can completely clean out your unit to ensure it works correctly and longer while reducing your energy costs. 

Unclogging the Line

If the unfortunate happens, and your portable conditioner’s condensate lines clog, you must unclog it before it causes serious damage to your unit.

Luckily, there are a few things you can do to remove the gunk that is inside. Some of these things are do-it-yourself (DIY) stuff that anyone can do. The others require a trained professional. 

DIY Measures

Before you call an HVAC technician, you want to see if you can deal with the clog yourself. Most condensate clogs are not huge.

It takes extraordinarily little to stop the flow through the small pipes. Therefore, a good shop vacuum may be enough to remove it.

However, you cannot just go in and use the vacuum. While that will remove the water, it may not remove the clog.

To clear the clog, you should follow these steps:

  1. Shut of the portable air conditioner and unplug it
  2. Inspect and clear the drain line for mold, leaves, and other debris
  3. Remove the water in the drain pan with your wet or dry shop vacuum
  4. Uncap the condensate line
  5. Inspect the line for any visible blockage
  6. Remove the blockage if one exists
  7. Use the vacuum to clear the pipe
  8. Pour a cup of bleach into the pipe
  9. Replace the cap

If you can easily remove the condensate line from the air conditioner without breaking it, you should take it out and complete these procedures outside.

You can then use a water hose to flush any debris that will remain. Just remember to not pour a drain cleaner as that can erode the inner lining of the pipe. 

When to Call a Professional

While you can fix most water problems by yourself, there are a few times where you must seek the help of a professional HVAC technician.

Typically, these moments arise with other methods fail. If you cannot unclog the pipes for instance. You also want a professional if the drain pumps break down as well.


Portable air conditioners are a great way to keep a room cool without permanently building an HVAC unit into a wall or window. However, like any air conditioner, they can quickly collect water. The water can come from either the natural operation of the unit or a clog in the condenser line. Both reasons are fixable using simple procedures that allow you to enjoy the cool air without that much extra work.