Locating the Drain on a Room Air Conditioner

When the audible alarm sounds and your unit shuts itself off, locating the drain on a portable or window room air conditioner becomes a vital task that must be done!

Why is that?

It's because if you don't drain the water from the condensate tank, the unit will not run (until that container is empty).

Why the Condensate Tank Fills with Water

room air conditioner drainAs it works to cool the air, a window or portable room air conditioner also does the job of dehumidifying that air.

Some air conditioning appliances have re-evaporation technology to deal with most of the moisture, but in high humidity, some water still gets past the system.

The moisture it removes from the air must go somewhere.

It's destination is a drainage pan, tank or container situated at the bottom of the unit. The tank would continually fill up and eventually overflow if there was no draining hole or other means for the water to be evacuated from the tank.

The speed that the container fills with water depends on how much humidity is in the air to begin with. The more moisture in the air, the faster the container will fill up as the AC unit works to cool the room.

Where the Drain Hole Should Be

If there is a hole in the unit, it will be beneath the condenser coils.

In a window AC, the condenser coils can be found in the section of the unit overhanging the outside of the building. In a portable AC, they are about a half to two thirds the way down inside the unit (depending on the make and model).

Most portable AC units have a visible drainage hole near the base of the unit at the back, to which a tube is attached for draining externally into a bucket (see manufacturer's manual of your model for details).

Slinger Ring

Some air conditioners are equipped with an alternate means of dealing with condensate, called a slinger ring.

A slinger ring would generally be attached to the rear fan blade. As the blade rotates, the ring collects water from the tray and, as the name suggests, slings it onto the condenser coils.

By doing this, the air conditioner recycles the water it creates by using it to assist in cooling the coils. This helps the machine to run with greater efficiency and prevents overheating.

These models also have a drain hole that is plugged during normal operation. It should only be unplugged when the water needs to be drained manually, if you need to move the unit or if for some reason the slinger ring is not working properly and the pan fills up.

Do Window Air Conditioners Need to Drain?

Most standard window AC models need to drain the excess water that is produced by condensation within the refrigeration process inside the unit.

However, the newer style of self-evaporating window units tackle this problem by re-evaporating the condensate and making use of it to aid the cooling process before ejecting it as water vapor out of the exhaust vent to the outside.

Locating a Window AC Drain Hole

Where is the drain hole on my AC? With a window AC unit it is necessary to go outside to locate the drainage hole.

It is sometimes connected to a drainage hose or tube. It that is the case, just follow the hose upward to the water container and there t will be.

If the AC has no drain hose attached, another way to find it is to look for dripping water, then follow the drips to their source. In some cases, if the pan is already overflowing, the water might be dripping from the drainage pan edges as well.

In any case, the most reliable way of finding the opening for draining water is to physically get underneath the AC and look up.

Accessing a Window AC Drain

Where do window AC units drain? It is usually not possible to access a window AC drain from inside the building without disassembling the unit, which can be a lot of work.

To access to the drainage hole from inside, it is easier to actually remove the air conditioning unit from the window than to take it apart.

No Drain Hole?

Do all air conditioners have a drain hole? Some AC units have no need of a drain at all. Some have theirs plugged if they do have one, for normal use.

One reason for not having a drain is a slinger ring and/or self evaporating technology is being used to deal with the moisture.

If your air conditioner's drainage hole is plugged, you should leave the plug in place. That's because the AC unit requires the water collecting in the pan to assist in its operation.

Only remove the plug if water overflows from the pan. If this happens, chances are the slinger ring is not working and needs to be repaired.

Keep the Drain Open

When a drain is the only way to empty water from the pan, it should stay open. If it becomes blocked, the water level will rise until it overflows.

When a self contained air conditioner has been in continuous service for a number of years, some internal components may rust. The rust can get into the drainage pan, collect on the bottom and block the opening.

Unblocking it can often be done with a small, stiff bottle brush or a large flat-head screwdriver.

However, if it blocks again, remove the back cover and get in there to clean any debris out of the pan.

Cleaning out the tank is easier to do if you first take the unit out of the window and put it on a workbench. If you must leave it in the window, you'll have to do the job from outside.

If that is the case, be sure to unplug the unit from the mains supply. Alternatively, before removing the cover to expose the drain pan, turn off the breaker located in the main panel that controls it.

Posted: June 13, 2021

Latest Update: February 19, 2023

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