Timer mode turns your AC on or off at a time you choose. The on-timer starts the unit after a delay or at a clock time, and the off-timer stops it, for example a few hours after you fall asleep. It changes when the AC runs, not how it cools.
Timer mode on an AC turns the unit on or off for you at a time you choose. The on-timer starts it after a delay or at a clock time, and the off-timer stops it, for example a few hours after you fall asleep. It changes when the AC runs, not how it cools.
On-timer and off-timer
Every remote manual we opened has both. Daikin's operation manual for its FTX30NVJU and FTX36NVJU sums up the point: timer functions are useful for switching the air conditioner on or off automatically in the morning or at night, and you can use the two together.
- Off-timer: shuts the AC off later. On GE and LG window units, you set it while the unit is running.
- On-timer: starts the AC later, usually with the mode, temperature and fan you used last. On GE and LG units, you set it while the unit is off.
Daikin confirms that last point: its on-timer begins with the settings used previously for mode, temperature, airflow rate and direction. GE's owner's manual for its ASH and ASW window models says the same, that the unit turns on at its previous setting.
Countdown timers vs clock timers
Makers set the time in one of two ways, and this is where most people get stuck.
Countdown timers count hours from now. MrCool's remote control user manual says each press adds 30 minutes up to 10 hours, then 1 hour at a time up to 24. Midea's window inverter manual uses the same steps. Older GE and LG window units go in whole hours from 1 to 12.
Clock timers use the time of day. On the Daikin remote you set the clock first, then pick the time in 10 minute steps. Daikin warns that the actual start or stop can differ from the set time by up to about 10 minutes.
Find a vetted local HVAC pro
Networx matches you with vetted pros near you. Free, no obligation.
How to set the timer: three makers' steps
MrCool mini split remotes
- Press Timer to start the on-time or off-time sequence.
- Press the temperature up or down button to set the hours. Five presses gives 2.5 hours.
- Point the remote at the unit and wait 1 second. The timer is set.
To cancel, set the timer back to 0.0 hours. MrCool's example combines both: at 1 PM, an on-timer of 2.5 hours and an off-timer of 5 hours start the unit at 3:30 PM and stop it at 6 PM. Both times count from now, not from each other.
Daikin (ARC466A37 remote)
- Check the remote's clock is correct.
- Press the On Timer (or Off Timer) button. The timer setting blinks on the remote screen.
- Press Select until the time reaches the one you want.
- Press the timer button again. The orange Timer lamp on the indoor unit lights.
Timer Cancel clears it. Daikin says to set the timer again after a power failure, after the circuit breaker has been turned off, or after you change the remote's batteries.
GE window units with touch pads
With the unit off, each touch of Timer adds one hour before it turns on, from 1 to 12. With the unit on, the same pad sets the hours until it turns off. To cancel, press Timer until the time disappears from the display.
The off-timer can change your temperature
On some units, setting the off-timer also nudges the set point, so you do not wake up cold. Check your manual, because this is easy to miss.
- LG: the LT series manual says that once the shut-off time is set, the temperature setting rises 2°F after 30 minutes and again after another 30 minutes.
- Daikin: its Night Set mode raises the set point 0.9°F in Cool (and lowers it 3.6°F in Heat) when you set the off-timer, to prevent overcooling while you sleep.
If you want that behavior without the unit shutting off, look at sleep mode on an AC, which works on a similar idea.
| Brand | Timer type | Range and steps | Where it is documented |
|---|---|---|---|
| MrCool | Countdown, on and off | 30 minutes to 10 hours, then 1 hour to 24 | Remote control user manual, page 7 |
| Midea (MAW window inverter) | Countdown, on or off | 0.5 hours to 10, then 1 hour to 24 | User manual, page 23 |
| Daikin (FTX NVJU) | Clock, on and off, plus weekly timer | 10 minute steps; up to 4 settings a day | Operation manual, pages 19 to 21 |
| GE (ASH, ASW) | Countdown, on or off | 1 to 12 hours | Owner's manual 49-7424, page 4 |
| LG (LT series) | Countdown, start or shut-off | 1 to 12 hours | LT series owner's manual, controls page |
Timer vs schedule on a smart AC
A timer is a one-off. It runs once and then you set it again. A schedule repeats.
Some units build a schedule into the remote. Daikin's weekly timer saves up to 4 settings for each day of the week, each with an on or off time and a temperature, and a copy mode repeats Monday's settings through Friday. Wi-Fi units do it in an app: Frigidaire's support page for its Frigidaire 2.0 app describes the app's Scheduler for room air conditioners, where your scheduled events are listed. Our roundup of smart air conditioners covers models with Wi-Fi control.
Central systems use the thermostat. The DOE's Energy Saver guide says a programmable thermostat turns the heating or cooling on at times you schedule and can store several daily settings, and a smart thermostat can learn your schedule and adjust on its own.
Does a timer save energy?
It can, by cutting hours you do not need. The DOE says you can save as much as 10% a year on heating and cooling by turning your thermostat back 7 to 10°F for 8 hours a day, and its summer tip is to raise the temperature when you are asleep or away. An off-timer at night, or a schedule that eases off while you are at work, is the room-AC version of that. If you would rather keep the unit running at lower power, eco mode is the other option.
There is one exception. ENERGY STAR's ductless heating and cooling page says heat pumps do not save energy by turning down when you are away or asleep, and recommends picking a comfortable temperature and leaving it. If your mini split heats your home in winter, go easy on the timer in heating season.
If a timer stops working after a power cut, set it again before assuming a fault, as Daikin advises. If the unit will not respond at all, try our steps to reset your air conditioner, and for the rest of the buttons, see our guide to AC modes.
Frequently asked questions
How do I set my AC to turn off after 2 hours?
Use the off-timer while the unit is running. On MrCool and Midea remotes, press Timer, then the temperature up button four times, since each press adds 30 minutes, and point the remote at the unit. On GE touch-pad window units, touch Timer twice. On a Daikin, set the off-timer to a clock time two hours from now.
Why didn't my AC turn on with the timer?
Check three things. The timer may have been cleared: Daikin says to set it again after a power failure, a breaker turned off or new remote batteries. On clock timers, the remote's clock must be correct. And on countdown timers, the hours count from when you set them, not from a time of day.
Can I use the on-timer and off-timer together?
Yes, on Daikin and MrCool units. Daikin's manual shows an off-timer at midnight with an on-timer at 2 PM the next day. MrCool's example starts the unit 2.5 hours from now and stops it 5 hours from now, both counted from the current time. Older GE window units set one or the other depending on whether the unit is on or off.
Is a timer the same as a schedule?
No. A timer runs once and has to be set again. A schedule repeats every day or week. Daikin's weekly timer saves up to 4 on or off times a day with a temperature for each, and Wi-Fi units such as Frigidaire's use a scheduler in the app. Central systems use a programmable or smart thermostat.
Founder of Home Caprice. Ben started the site to simplify HVAC after dealing with the heating and cooling in his first apartment.