Anti-mildew mode keeps the indoor unit running at very low power after you turn the AC off from Cool, Auto or Dry, so the wet coil dries and mildew has less to grow on. Midea, Senville and MrCool call it anti-mildew, Gree calls it X-FAN, and LG calls its version Auto Clean. It dries the coil but does not clean it or remove existing mold.
Anti-mildew mode keeps your air conditioner's indoor unit running at very low power for a while after you turn it off from Cool, Auto or Dry, so the wet coil dries out and mildew has less to grow on. On the units that have it, it usually runs by itself when you switch off from a cooling mode. It is a drying feature, not a cleaning one, and it will not remove mold that is already there.
How anti-mildew mode works
When your AC cools, water from the room air condenses on the cold indoor coil. That water drains away while the unit runs, but the coil is still damp when it stops. Anti-mildew mode uses airflow to dry it before the unit goes fully quiet.
Midea's US split owner's manual describes it this way: when you turn the unit off from COOL, AUTO (COOL) or DRY, it "continues to operate at very low power to dry up any condensed water and prevent mildew growth." Senville's LETO owner's manual uses almost the same words, and MrCool's 4th Gen DIY multi-zone manual says the same for COOL, DRY or AUTO. All three list it as a feature on "some units."
None of those three manuals gives a run time. Gree, which calls the feature X-FAN, says in its LIVO Gen4 owner's manual that the indoor fan keeps running "for a few minutes at low speed" after you switch off. LG's version runs in fan mode and turns the unit off after 10 minutes on its LED lamp models, according to LG's US support page for the Co code.
Anti-mildew vs self-clean
The two get mixed up because brands do not use the names the same way. Some makers keep them as two separate functions:
- Midea lists Anti-mildew and Active Clean as different features. Active Clean freezes the coil, thaws it to rinse off dust, then dries it with hot air for 20 to 45 minutes.
- Gree has X-FAN for drying and a separate Auto Clean that "will cool down and heat up rapidly."
- Pioneer puts separate Anti-Mildew and Self-Cleaning buttons in its Airlink app.
Other makers give the drying function a cleaning name. LG calls its fan-only drying cycle Auto Clean on its Auto Clean help page, and the US page calls the same thing auto drying. Fujitsu's COIL DRY, in its ASU9RL and ASU12RL manual, dries the indoor unit "so as to avoid going moldy," runs for 90 minutes, and starts from a button rather than automatically.
| Brand | Drying after shut-off | Separate deep-clean cycle |
|---|---|---|
| Midea | Anti-mildew (some units) | Active Clean |
| MrCool | Anti-Mildew (some units) | Active Clean |
| Senville | Anti-mildew (some units) | Self-cleaning, in the remote manual |
| Gree | X-FAN | Auto Clean (LIVO Gen4) |
| Pioneer | Anti-Mildew (app) | Self-Cleaning (CLEAN button) |
| LG | Auto Clean or auto drying | None found in the pages we opened |
So if your remote has only one "clean" function, check the manual to see which kind it is. Our self-clean mode guide covers the deep-clean cycles and how long each brand's runs.
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When it runs, and why the fan keeps going
Anti-mildew works after cooling, not heating. Midea, Senville and MrCool tie it to switching off from Cool, Auto (Cool) or Dry. Gree says X-FAN "is not available in AUTO, FAN or HEAT modes."
This is the main thing owners notice: you press off and the fan keeps blowing. That is the feature working. On Gree units you can stop it early by holding the fan speed button for 2 seconds during that period. LG warns its cycle may not run if the unit stops on a timer or sleep setting.
If the indoor unit keeps running far longer than a few minutes, or will not respond to the remote, try our steps to reset your air conditioner before calling for service.
How to turn anti-mildew on
It depends on the brand:
- Midea, Senville, MrCool: the manuals list it under features rather than as a button, so on units that have it, it works when you switch off from a cooling mode.
- Gree: in COOL or DRY, hold the fan speed button for 2 seconds until the X-FAN icon shows. Gree says X-FAN is off by default after start-up.
- Pioneer: tap Anti-Mildew in the Airlink app; Pioneer says it starts after you turn the unit off and stops on its own.
- Fujitsu: press COIL DRY during operation or after the unit stops.
Brands that have anti-mildew mode
These are the brands where we found the feature in a manual or on an official support page, under each maker's own name:
- Anti-mildew: Midea, Senville and MrCool, each on "some units."
- Anti-Mildew in the app: Pioneer.
- X-FAN: Gree, on the LIVO Gen4 and the VIREO Gen3 wall units.
- Auto Clean or auto drying: LG.
- COIL DRY: Fujitsu, on the ASU9RL and ASU12RL.
One naming trap: a "mildew" label on the spec sheet does not always mean this mode. Fujitsu's same manual lists a mildew-resistant filter, meaning the air filter "has been treated to resist mildew growth." That is a filter material, not a drying cycle. If you are shopping, check the owner's manual for the function itself rather than the feature list.
What anti-mildew will not do
It slows mildew; it does not remove it. Fujitsu states that COIL DRY "cannot get rid of the existed mold or bacterium, and it has no sterilization effect either." It also leaves the drain and the filter to you.
The EPA's guide to mold and moisture says "the key to mold control is moisture control." It advises keeping indoor humidity below 60 percent, ideally 30 to 50 percent, and keeping AC drip pans clean and drain lines flowing. For room humidity, look at dry mode, which Panasonic's CS-XZ manual says runs with humidity control when the fan is set to AUTO.
If the unit already smells musty or you can see mold, read our guide on getting rid of mold in an AC. For the other buttons on your remote, see our guide to every AC mode.
Frequently asked questions
Is anti-mildew the same as self-clean?
Not always. Midea, Gree and Pioneer treat them as two functions: anti-mildew (X-FAN on Gree) dries the coil after shut-off, and a separate cleaning cycle does the deeper job. Midea's Active Clean, for example, freezes, thaws and then dries the coil. LG uses the name Auto Clean for what is a fan-only drying cycle. Check your manual to see which kind your button runs.
Why does my AC fan keep running after I turn it off?
Most likely the anti-mildew or X-FAN feature is drying the coil. Midea, Senville and MrCool say the unit keeps running at very low power after you switch off from Cool, Auto (Cool) or Dry. Gree says the fan runs a few minutes at low speed, and LG's drying cycle turns the unit off after 10 minutes on LED lamp models.
Does anti-mildew mode work in heat mode?
No, in the manuals we checked it is tied to cooling. Midea, Senville and MrCool describe it running after you switch off from Cool, Auto (Cool) or Dry. Gree states that X-FAN is not available in AUTO, FAN or HEAT modes. If your unit is set to heat and the fan keeps going after shut-off, check the manual for what your model is doing.
Can I turn anti-mildew mode off?
On Gree units, yes: X-FAN is off by default after start-up, you switch it on by holding the fan speed button for 2 seconds in Cool or Dry, and holding it again during the drying period stops the fan. Midea, Senville and MrCool describe it as a feature of some units rather than a button, so check your remote manual.
Founder of Home Caprice. Ben started the site to simplify HVAC after dealing with the heating and cooling in his first apartment.