Symptoms
- Musty odor when the unit turns on
- Smell circulates through the room while running
- Visible grime on the filter or in the bucket
- Smell stronger after the unit sat unused
Likely causes
- CommonMold or mildew on the filterA dusty, damp filter is a common mold spot.
- CommonStanding water left in the bucket for daysStagnant water grows odor-causing bacteria and mold quickly.
- PossibleMold on the internal coilCondensation on the coil that isn't fully drained supports mold growth.
- PossibleUnit stored with moisture left insideOff-season storage without drying out first invites mold.
What to do
- Unplug the unit, empty the bucket, and wash it with warm soapy water, rinsing thoroughly.
- Remove the filter and wash it separately, letting it dry fully before reinstalling.
- If the coil is accessible, wipe it with a cloth dampened in a diluted vinegar solution and let it air dry.
- Empty the bucket daily or as often as needed so water doesn't sit for multiple days.
- Run the unit in a room with good airflow for a while after cleaning to help dry out the interior.
- Before storing off-season, run the unit until fully dry inside and store the bucket separately and dry.
Tools and parts
- Mild dish soap
- Soft cloth
- White vinegar (optional)
Replacement dehumidifier filterSearch: “dehumidifier filter replacement”
When to call a pro
Call an appliance technician if the musty smell persists after cleaning the bucket, filter, and accessible coil, since mold may be deeper inside.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.