Forced-air systems run the fan whenever they're heating or cooling. If your forced air system has a separate fan wire in your Nest thermostat's G terminal, you can run the system fan when it's not heating or cooling. If not, your fan will only run automatically when your system is heating or cooling.
If you have a system with a dedicated fan wire, you can manually turn on the fan with the app or your thermostat, or set a fan schedule. For example, you can set the fan to run all night and automatically turn off in the morning.
Important things to know about fan control
If there's a wire in your thermostat's G terminal
- You can run your system's fan independently of heating or cooling. This allows the fan to run even when heating or cooling isn't active.
- Fan timer can start even if the thermostat is set to Off .
- You can set the fan to run a fixed schedule or manually set it to run. However, your fan can’t start based on schedule if the thermostat is set to Off.
Tip:Fan schedule can't be set to automatically run or switch off when you leave or come home .
- The temperature screen will show a fan icon when your fan is running because of your fan schedule, or if you've turned your fan on manually. Learn about Nest thermostat displays .
If there isn't a wire in your thermostat's G terminal
- The fan can only run while your system is actively heating or cooling.
- Fan control options won't be shown on your thermostat or in the app.
Fan settings enhance comfort and energy efficiency
Longer fan usage may help to even out the temperatures between rooms in your home, but the fan can use a lot of energy and increase your electric bill.
Extended fan usage will increase your system's runtime, which may require you to replace the air filter sooner. To help you know when it's time to replace your system's filter, refer to Air filters and filter reminders .
Fan controls differ slightly depending on which thermostat you have . Select your thermostat below.
Nest Thermostat
- Select your thermostat's touch bar and select Fan
.
- Select how long you'd like your fan to run, then tap Confirm.
- Choose Startto run the fan or Cancel.
- Your fan automatically turns off when the set time expires. Select Stopfrom the fan menu to turn it off sooner.
Tip:When the fan is turned on manually, your Nest Thermostat allows it to remain active even when the thermostat is set to Offmode.
Nest Learning Thermostat and Thermostat E
Turn your fan on manually
- Press your thermostat ring to open the Quick View menu.
- Select Fan
- Turn the ring to select how long you'd like your fan to run.
- If you have a multi-speed fan , you'll also be able to set your fan speed.
- Your fan will turn off automatically after the time you've selected.
- Select Stop Fanto turn off the fan early from the fan menu.
Your thermostat's screen will show a spinning fan icon to let you know it's functional.
Set a daily fan schedule (available only on certain thermostats)
- Press your thermostat ring to open the Quick View menu.
- Select Settings .
- Select Fan.
- Choose Schedule.
- Set how long you'd like your fan to run per hour, or set it to always run.
- Select what hours of the day you'd like your fan to run. If you have a multi-speed fan , you can select a fan speed for your fan schedule.
- Select Doneto set your schedule.
Your fan will turn on automatically each day for the time and duration you've selected.
Change the fan speed (available only on certain thermostats)
For example, you can set your fan to high when heating or cooling and schedule your fan to run at low speed in the morning to circulate the air in your home.
Learn more about the Nest Thermostat and multi-speed fans
- Press your thermostat ring to open the Quick View menu.
- Select Settings.
- Select Fan.
- Choose System fan speed.
- Select the fan speed you'd like to use when your system is heating or cooling your home. Depending on your system, it may show Low, Medium, Highor Autoif you have a multi-speed fan.
- Choose Doneto set your system's fan speed.
Turn your fan on manually
- Open the Google Home app
.
- Touch and hold your device's tile.
- Tap Fan
- Choose how long you'd like your fan to run.
- Tap Run fanto run your fan or tap outside the sheet to cancel.
- The fan automatically turns off after the set time. To manually turn off the fan, tap Fan
End fan.
Set a daily fan schedule
- Open the Google Home app
- Touch and hold your device's tile.
- Tap Settings
.
- Select Schedules
- Nest Learning Thermostat (3rd gen) and Nest Thermostat E: Select Schedules
All other Thermostat models: If you want to set the same fan schedule for all days, turn on Run every day. You can turn it off if you want a unique schedule for a particular day.Important:If you have the Nest Learning Thermostat (3rd gen) or Nest Thermostat E, you won’t be able to set a different schedule for different days.
- Choose a start and end time with "From" and "To".
- Set how long you'd like to run your fan per hour. You can choose 15, 30, 45, or 60minutes of operation.
Your fan turns on automatically each day for the time and duration you select. You can edit or disable your schedule at any time from the fan menu.
Change the fan speed
Important:This setting is only available for systems with multi-speed fan controls over the thermostat wires. This affects the fan speed when your system is actively heating and cooling. You'll have separate options to set the fan speed each time you manually turn on your fan or if you set a fan schedule.
- Open the Google Home app
- Tap and hold your device's tile.
- Tap Settings
- Under System fan speed, select the fan speed you want to use when your system heats or cools your home. You can choose Low, Medium, High, or Auto based on your system's wiring.
If you choose Low, Mediumor High:
- Your fan runs at that speed when it heats or cools your home.
If you choose Auto:
- Your Nest thermostat automatically chooses how fast to run your fan when it heats or cools your home.
You can still choose a different speed for your schedule and each time you manually operate your fan.
Turn your fan on manually
- Tap the thermostat you'd like to control from the home screen.
- Tap Fan
- Select how long you'd like your fan to run. If you have a multi-speed fan , you'll be able to select your fan speed.
- Tap Startto run your fan.
Your fan will turn off automatically after the time you've selected, or you can turn it off early by selecting Stopfrom the fan menu.
Set a daily fan schedule
- Tap the thermostat you'd like to control from the home screen.
- Tap Settings .
- Select Fan Schedule.
- For Every day, tap the slider to turn your fan schedule on or off.
- Set how long you'd like to run your fan per hour. You can choose 15, 30 or 45 minutes of run time, or select 60 minutes to run your fan for the whole hour.
- Choose what time you want your fan to start running, and when you'd like your fan to stop running this schedule. If you have a multi-speed fan , you can select a fan speed for your fan schedule.
Your fan will turn on automatically each day for the time and duration you've selected. You can always edit or disable your schedule at any time from the fan menu.
Change the fan speed
Important:This setting is only available for systems with multi-speed fan controls over the thermostat wires. This affects the fan speed when your system is actively heating and cooling. You'll have separate options to set the fan speed each time you manually turn on your fan or if you set a fan schedule.
- Tap the thermostat you'd like to control on the app home screen.
- Tap Settings .
- Select Fan.
- In HVAC fan speed, select the fan speed you'd like to use when your system is heating or cooling your home. You can choose Low, Medium, Highor Autodepending on your system's wiring.
If you choose low, medium or high:
- Your fan will always run at that speed when heating or cooling your home.
If you choose Auto:
- Your Nest thermostat will automatically choose how fast to run your fan when heating or cooling your home.
You'll still be able to choose a different speed for your schedule and each time you manually run your fan. For example, use a high fan speed for heating or cooling, and schedule a low fan speed for daily air circulation.
When you set up the Nest Learning Thermostat (4th gen), you'll be asked if your fan is to be controlled ‘By furnace’ or ‘By thermostat’. If you test your furnace and notice the fan isn't activating, you can change this in your thermostat’s ventilation settings in the Google Home App. Test your system with a Nest thermostat .
For more information about Furnace heads-up, refer to Troubleshoot Furnace Heads-Up message .
