Clean-filter reminder
A reminder that the air filter is due for cleaning. After cleaning, you reset it by hand.
What to do when it shows
Take the filter out, vacuum or wash it and let it dry, refit it, then reset the reminder: Toshiba with the Filter button, Fujitsu by pressing the indoor unit’s manual AUTO button for under 3 seconds, Samsung from the remote’s options. Samsung says to clean every two weeks or when the reminder appears.
What it does not do
It does not measure how dirty the filter is: Toshiba’s light comes on after 250 hours of operation whatever the filter looks like, so a dusty room may need cleaning sooner.
Makes differ, check your unit’s manual: the same drawing can mean different things on different brands, and only your model’s manual says exactly what a button does and which modes it works in.
- What it looks like
- Letters such as CF on the indoor unit’s display (Samsung), or a lamp next to the word FILTER (Toshiba).
- Names makers use
- Filter reset indicator CF (Samsung); Check Filter (Toshiba); Filter indicator (Fujitsu)
Where makers differ
Samsung writes CF on the display, Toshiba lights a Check Filter lamp; the hour count and reset method are the maker’s. This is a status message, not an error code.
Other symbols with the same shapes
Sources
No single published standard defines air-conditioner remote icons, so this meaning is taken from 3 makers’ own manuals, each fetched and read on the date shown:
- Samsung: Samsung — Wind-Free 2.0 air conditioner user manual, AR**TSFA*** (PDF on Samsung HVAC’s document store) — Indoor display: “Filter reset indicator (CF)”; “Clean the air filter every two weeks or when the (filter-cleaning reminder) appears on the indoor unit display … Reset the filter-cleaning reminder.” Checked 2026-09-26.
- Toshiba: Toshiba — RAC-WK1513ESCWRU window air conditioner user manual (PDF) — CHECK FILTER FEATURE: “a reminder to clean the air filter … The light will illuminate after 250 hours of operation. After cleaning the filter, press the Filter button to reset the Check Filter function turning the light off.” Checked 2026-09-26.
- Fujitsu General: Fujitsu General — Operating manual, wall-mounted 18/24RLB and 30/36RLXB (US, PDF) — Manual AUTO button on the indoor unit: “After cleaning — Press less than 3 seconds — Filter indicator reset.” Checked 2026-09-26.
Written in our own words; quotations are the makers’ wording.