Symptoms
- Water dripping or pooling under the unit indoors
- Wet spot on the wall or windowsill
- Dripping increases on humid days
- Water stains on the floor below
Likely causes
- CommonUnit not tilted slightly toward the outsideWindow units need a slight backward tilt so condensate drains outward, not inward.
- CommonClogged internal drain hole or panDust and mineral buildup can block the small drain that lets water exit the back.
- PossibleDirty filter causing coil to over-condense or ice upA frozen coil that then melts can overwhelm the drain pan.
- PossibleDamaged or missing foam side panelsGaps let humid outside air in and change how condensation drains.
What to do
- Turn off and unplug the unit before inspecting it.
- Check the installation: the outside edge of the unit should sit slightly lower than the inside edge (about a half-inch), not level or tilted inward.
- Adjust the mounting brackets or shims so the unit tilts toward the outdoors, then retest.
- Remove the filter and front cover and look for a clogged drain hole in the base pan; clear debris with a small brush or pipe cleaner.
- Clean or replace a dirty filter, since ice buildup on the coil is a common hidden cause.
- Reinstall the foam side panels snugly to seal the window opening.
- Run the unit for an hour and recheck for leaking before closing everything back up.
Tools and parts
- Small brush or pipe cleaner
- Level
- Shims
When to call a pro
Call an appliance technician if the drain pan or coil is cracked, since that requires disassembling the sealed system.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.