TCL window AC modes explained: Cool vs Eco vs Auto vs Dry vs Fan

The short version

On TCL’s electronic window and through-the-wall air conditioners, Cool cools to the temperature you set, and its fan may keep running after the room gets there; Eco cools to that temperature and then shuts the unit off, fan included, until the room warms up again; Auto lets the unit pick Cool, Dry or Fan from the room temperature; Dry takes moisture out of the air with short cooling bursts; and Fan only moves air and doesn’t cool at all. Heat exists only on heat/cool through-the-wall models.

If the fan keeps stopping and starting, the unit is almost certainly in Eco: that’s how Eco is designed. If you want steady airflow, switch to Cool.

Which button selects which mode, and why Dry is only on the unit’s panel, is covered in the TCL remote buttons guide. This page explains what each mode does once it’s on.

The modes side by side

Mode	Does it cool?	What the fan does	Set temperature
Cool	Yes, and it lowers humidity at the same time.	Runs at the speed you pick (Hi, Med, Lo or Auto). It may keep running after the room reaches the set temperature.	You choose it, 61 to 88 °F (16 to 31 °C).
Eco	Yes, until the room reaches the set temperature; then the unit turns off.	Stops with the unit, then runs now and then (see below).	You choose it.
Auto	Only when the unit decides Cool or Dry is needed.	UH and through-the-wall manuals say Auto picks the fan speed too.	Set automatically from the room temperature.
Dry	In short cycles, alternating with fan-only running.	Alternates with the cooling cycles.	Not explained in the remote manuals; the Smart Life app guide says it is fixed at 61 °F (16 °C).
Fan	No.	Hi, Med or Lo; no Auto speed in Fan.	Not described for the remote; the display shows the room temperature instead.
Heat (heat/cool through-the-wall only)	No, it heats.	Hi, Med, Lo or Auto (TTW quick-start guide).	You choose it.

The fixed temperatures in the app aren’t mentioned in the remote manuals. The Smart Life guide gives Dry 61 °F and both Fan and Auto 73 °F (23 °C), none adjustable; the TCL Home Comfort guides say only that those three are preset. Cool, and Heat on heat models, can be set freely.

Cool vs Eco: why the fan stops or keeps going

Both modes cool the room to the temperature you set. The difference is what happens once it gets there.

• In Cool, the compressor cycles on and off to hold the temperature, and the fan can keep blowing in between. TCL’s quick-start guides say that without Eco, the fan may continue to run after the room reaches the set temperature, and TCL’s manuals list “the fan may run even when the compressor is not on” among the normal operating sounds. Expect steady air movement and the fan noise that goes with it.
• In Eco, the whole unit switches off at the set temperature and back on when the room warms past it. The Eco light on the unit stays on while Eco is active. Before the compressor restarts, the fan runs for a while, stops, and repeats. TCL presents this as the energy-saving option.

So a fan that goes quiet and then starts again by itself is Eco doing its job, not a fault. Exactly what the fan does while the unit is “off” in Eco differs a little between TCL’s documents (some say the fan is off too, the quick-start guides say it runs for a few seconds now and then to take a temperature reading); the Eco differences by manual are listed in the remote buttons guide. None of the manuals says whether Eco can be combined with Dry, Fan, Auto or Heat; TCL describes it only for cooling.

Auto: what the unit decides for you

In Auto, the unit reads the room temperature with its own built-in sensor and chooses Cool, Dry or Fan by itself. The UH and through-the-wall manuals add that it also chooses the fan speed. TCL doesn’t publish the room temperatures at which Auto switches from one to another.

Two limits worth knowing:

• Auto never heats. It chooses only between Cool, Dry and Fan. On heat/cool through-the-wall remotes, the Auto Mode button is replaced by Heat; the TTW-…/UF manual’s remote list marks Auto Mode as for cooling-only models. Its drawing of the heat-model control panel still shows an Auto Mode light, but the manual doesn’t say how Auto is chosen on those units.
• You can’t steer it with the set temperature. TCL says the temperature is set automatically in Auto, and the app guides list Auto as preset and not adjustable. If you want a specific temperature, use Cool or Eco.

Dry: for humid days that aren’t hot

Dry lowers the humidity by alternating short cooling cycles with fan-only running, so it takes moisture out without chilling the room as hard as Cool. TCL doesn’t say what fan speed Dry uses or how much cooler the room gets. Choose it with the Mode button on the unit’s control panel; the remote has no Dry button. Through the app, the Smart Life guide says the Dry set temperature is fixed at 61 °F.

Cool also dehumidifies, so you don’t need Dry on a hot, humid day; Cool does both.

Fan: moving air without cooling

Fan mode only circulates the room’s air; it doesn’t cool. You can choose Hi, Med or Lo; Auto speed isn’t offered in Fan. While the unit is in Fan mode, the display shows the room temperature (except while you’re setting the timer, and on UH and TTW-…/UF units also while you set the temperature).

TCL’s manuals add that Fan mode “only works when the air conditioner is vented”, without explaining what that means for a window or through-the-wall unit. We couldn’t establish it from the documents.

Which mode to use (our suggestions)

These are our suggestions, not TCL’s, based on how TCL describes each mode:

Situation	Try
Hot room, you want it cool quickly and steady airflow	Cool, with a higher fan speed
Hot room, you’d rather save energy and don’t mind the fan cycling	Eco
Sticky, humid but not very hot	Dry (from the unit’s panel)
Mild weather, you just want air moving	Fan
Cool weather outside (below 65 °F)	Fan, not Cool (see below)
You don’t want to decide	Auto
Cold room on a heat/cool through-the-wall model	Heat

For nights, Sleep changes the set temperature on its own over several hours; it isn’t a separate mode. See what Sleep does in the remote buttons guide.

Before you switch modes

• Wait 3 minutes between mode changes. TCL asks for this to keep the compressor from overheating and the circuit breaker from tripping. The same 3-minute wait applies after you switch the unit off before switching it on again.
• Don’t cool when it’s below 65 °F (18 °C) outside. The TAW 8K–12K and UH manuals warn that the inside coil will freeze and the unit won’t work properly. If ice does build up, TCL’s troubleshooting tables say to set high fan or high cooling and a higher set temperature; the TCL window AC troubleshooting guide has the details.
• After a power cut, the same manuals say the unit restarts with its previous settings, so it comes back in the mode it was in.

Common questions

Why can’t I find Dry on my remote?

TCL’s window and through-the-wall remotes have no Dry button; choose Dry with Mode on the unit’s control panel, as explained in the remote buttons guide.

My unit stopped cooling but the light is still on. Is it broken?

If the Eco light is on and the room is at or below the set temperature, the unit has switched itself off as Eco is meant to, and it restarts when the room warms. If it’s in Cool and still not cooling, or it won’t restart at all, start with the TCL window AC troubleshooting guide. TCL’s troubleshooting tables also note a protective delay of about 3 minutes before normal cooling starts after the unit is switched back on.