Why Is My Indoor AC Unit Dripping Water?

How Air Conditioners Function

• A major function of the air conditioner is to cool the air inside a room. But just as important a function is how the unit dehumidifies the room, removing water vapor from the air and condensing it into liquid. When the air conditioner squeezes this moisture from the room air, it reduces the room's humidity level and room inhabitants feel less of the "sticky" feeling that accompanies high humidity. The water that results from this removal leaves the air conditioner through a drain hole.

Where the Water Drips

• The water that drips out of the air conditioner should drip to the outside, not to the inside of the room. If it does drip onto the inside, it can potentially lead to mold and mildew problems and even rotting wood. If you notice the water dripping inside, adjust the air conditioner so that the front of the unit is slightly raised, tilting the back of the unit down slightly lower than the front. Some units also have a tube or fitting attached to the drain hole to direct the flow of the dripping water.

If the Dripping Stops

• If the air conditioner normally drips, then stops, there may or may not be a problem with the unit. If the humidity level inside the room is low, the room air does not contain a lot of moisture for the air conditioner to remove. Another possibility that requires attention is a stopped-up drain hole or tube, which will cause the unit to not properly remove moisture from the room air, possibly leading to carpet and wall damage from the excess moisture. Also, water will back up and eventually drip inside the room, especially when the unit is not tilted properly. In that case, the drain hole or tube needs to be cleared.

Maintenance

• Some of the newer air conditioners are designed so that the water inside the unit evaporates against the unit's inner condenser coils instead of dripping out. However, if your particular unit is designed for the water to drip out the back, performing routine maintenance helps the unit drain properly by ridding it of its enemy, dirt. Insert the end of a wire hanger into the drain hole to clean it out. Also clean the channels through which the water drains through the unit.