How to Lock Fujitsu Thermostat: A Comprehensive Guide

Locking your Fujitsu thermostat is a simple yet effective way to prevent unauthorized changes to your HVAC system’s settings, ensuring optimal performance and energy efficiency. This comprehensive guide will walk you through the step-by-step process of locking and unlocking your Fujitsu thermostat, providing you with the technical expertise and practical knowledge to take control of your home’s climate.

Accessing the Monitor Screen

The first step in locking your Fujitsu thermostat is to access the “Monitor” screen. To do this, press and hold the “Cancel” button on your thermostat for 2 seconds or more. This will bring you to the “Monitor” screen, where you can then proceed to enable the key lock function.

Enabling the Key Lock Function

how to lock Fujitsu thermostatImage source: Fujitsu AC by Dinkun Chen

Once you’re on the “Monitor” screen, press and hold the “Cancel” button for another 2 seconds or more. This action will enable the key lock function, effectively locking your thermostat’s settings and preventing any further changes.

Verifying the Key Lock Status

After enabling the key lock function, it’s important to verify that the lock is indeed active. You can do this by checking the display on your Fujitsu thermostat. If the key lock icon is visible, it indicates that the thermostat is successfully locked and secured.

Unlocking the Fujitsu Thermostat

When you need to make changes to your thermostat’s settings, you’ll need to unlock the device. To do this, simply repeat the process of accessing the “Monitor” screen by pressing and holding the “Cancel” button for 2 seconds or more.

Disabling the Key Lock Function

Once you’re on the “Monitor” screen, press and hold the “Cancel” button for another 2 seconds or more. This action will disable the key lock function, allowing you to make the necessary adjustments to your thermostat’s settings.

Verifying the Unlock Status

After disabling the key lock function, check the display on your Fujitsu thermostat to ensure that the key lock icon is no longer visible. This confirms that the thermostat is now unlocked and ready for you to make changes as needed.

Importance of the Key Lock Function

The key lock function on your Fujitsu thermostat is designed to prevent accidental changes to the settings, particularly by children or unauthorized individuals. By locking the thermostat, you can ensure that your HVAC system’s performance and energy efficiency are maintained, even in high-traffic areas of your home.

Recommended Practices

It’s important to note that while the key lock function is a valuable feature, it’s recommended to release the lock when actively operating the thermostat. This allows you to make any necessary adjustments to the temperature, schedule, or other settings as needed to maintain your desired indoor climate.


If you encounter any issues while locking or unlocking your Fujitsu thermostat, refer to the manufacturer’s user manual or contact their customer support for further assistance. The manual may provide additional troubleshooting steps or guidance specific to your model.


Locking your Fujitsu thermostat is a simple yet effective way to protect your HVAC system’s settings and ensure optimal performance. By following the step-by-step instructions outlined in this comprehensive guide, you can easily lock and unlock your thermostat, giving you the peace of mind and control you need over your home’s climate.


  1. Fujitsu Thermostat User Manual
  2. Fujitsu Thermostat Key Lock Tutorial
  3. Fujitsu Thermostat UTY-RNRYZ1 User Manual
  4. Fujitsu Thermostat OM_9380221012-03_En Manual
  5. Fujitsu Thermostat Locking Demonstration