Defrost indicator (dF or blinking lamp)
The heat pump has paused heating for a few minutes to melt frost off the outdoor unit’s coil. Heating resumes by itself.
What to do when it shows
Nothing to do; wait. Samsung runs it for 5 to 12 minutes, Fujitsu up to 15. Steam rising from the outdoor unit, a sizzling sound and water dripping from it are normal during defrost, and the indoor fan stops or the flap closes so cold air is not blown at you.
What it does not do
It is not a fault or an error code, and it does not mean the unit has stopped heating for good: the outdoor coil is defrosting and heating restarts on its own.
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
- The letters dF on the indoor display (Samsung), or the green OPERATION or POWER lamp blinking while heating (Fujitsu, Airwell, Panasonic).
- Names makers use
- Defrost indicator dF (Samsung); Automatic defrosting (Fujitsu); Defrosting (Airwell); Intelligent Defrost (Gree)
Where makers differ
Only some units show a symbol; most signal it with a blinking lamp. Panasonic says the POWER indicator blinks with no warm air and the flap closed; Samsung shows dF and blocks remote changes until it ends.
Often confused with
The unit runs as a heat pump and warms the room towards the set temperature, taking heat from the outdoor air.
Other symbols with the same shapes
Sources
No single published standard defines air-conditioner remote icons, so this meaning is taken from 4 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) — “the air conditioner runs the Defrost function for 5 to 12 minutes to remove frost from the outdoor heat exchanger … the (Defrost) indicator appears on the indoor unit display, steam is produced on the outdoor unit.” Indoor display legend: “Defrost indicator (dF)”. Checked 2026-09-26.
- Fujitsu General: Fujitsu General — Operating manual, wall-mounted 18/24RLB and 30/36RLXB (US, PDF) — Automatic defrosting: “defrost circuit will operate briefly (maximum of 15 minutes.) OPERATION indicator on the indoor unit blinks during this operation”; sizzling sound and rising steam are normal. Checked 2026-09-26.
- Airwell: Airwell — RC08W remote control manual (PDF) — Defrosting: “the fan in the indoor unit stops and the OPERATION lamp is flashing until defrosting is completed. Heating operation restarts after several minutes.” Checked 2026-09-26.
- Panasonic: Panasonic — Operating instructions, CS-Z*AKUAW air conditioner (North America, PDF) — Troubleshooting, not a malfunction: “POWER indicator blinks during HEAT mode with no warm air supply (and flap is closed) — The unit is in defrost mode.” Checked 2026-09-26.
Written in our own words; quotations are the makers’ wording.