Why Isn't Water Draining From My Window AC Unit?

Improper Installation

• If you don't see drainage falling from the back of the window unit, then it's possible the water is draining fine from the unit, but not in the correct direction. The unit should be tilted back slightly or, at the most, level. If the unit is tipped forward a bit, then the drainage runs down the bottom of the unit toward the wall. This is bad, as the drainage might flow directly into the house or damage the exterior wall. A readjustment of the unit will fix this problem.

Little Humidity

• Moisture might not be readily available to pull from the air if outside and inside air are void of humidity. If no moisture is in the air, then little to no drainage can be created within the drain pan, which is located at the back of the unit. Thus, if water doesn't accumulate because of a dry climate, it's no indication that the air conditioner functions improperly.

Slinger Fan

• Toward the back of the window unit air conditioner near the drain pan is a slinger fan. The slinger fan picks up the water in the drain pan, if the drain pan is full, and flings it toward the condenser for expulsion. If the slinger fan fails to run, then the excess water in the drain pan overflows and could be running loose inside of the air conditioner, which is bad, because the water potentially could damage important internal components. If the air inside the home is humid and the unit fails to drain, then the slinger fan could be broken and should be repaired.

Drain Pipe

• Some units feature a drain pipe portal at the back of the unit near the drain pan. If water accumulates excessively in the drain pan, a drain pipe can be inserted into the portal to allow excess moisture to drain from the overflowing drain pan. If you live in a humid area, it's a good idea to insert the drain pipe upon installation. If it's not installed, the drain portal cap can be removed and then the drain pipe pushed into the portal. Water from the drain pan drains from the drain pipe.