Why Does My Window Air Conditioner Leak Water?

Ice Buildup

• Occasionally ice will build up inside your air conditioner. When this happens, the ice slowly melts, causing the air conditioner to leak. If you suspect ice buildup is the problem with your air conditioner, turn the appliance off to allow it to thaw out. This is the same concept as ice buildup in your refrigerator or freezer. Place a container underneath the air conditioner to catch any moisture that might drain out as the ice thaws. Clean the air conditioner well, taking extra care around clogged grilles after thawing before turning it back on.

Imporper Installation

• One of the reasons that a window air conditioner may be leaking is a problem with the installation. The front of the window unit -- the part that is inside your home -- should be a little higher than the back that hangs out the window. Keep the front of the air conditioner about 1 inch higher than the back to allow for proper drainage of moisture.

AC Is Not Airtight

• If the window space around your air conditioning unit is not airtight, this is a cause for water leaking as well. Inspect the space between the air conditioner and the window casing, and seal up any opening using foam. Use spray foam if you leave the units in the window year-round, or use cutup pieces of 2-inch thick foam if you remove your air conditioner in the winter months.

Blocked Drains

• An air conditioner has drains both on the inside of the unit and the drain hole that prevent moisture buildup from happening in the first place. From time to time, these holes get blocked from dust and other debris, such as pieces of leaves or bugs. If this is the case, all your air conditioner needs is a simple cleaning. Unplug the air conditioner, and remove it from the window. Remove the grilles using a screwdriver, and clean out all the drainage holes. Turn the air conditioner back on after replacing it in the window.