Carrier thermostat control panels come with a built-in "button lock" for preventing accidental changes to your home temperature settings. The button lock also stops children or others in your home from changing the thermostat settings without permission. Unlocking your Carrier thermostat "button lock" enables you to adjust your home temperature settings as well as other options incorporated into your thermostat control panel.
Locate the "MODE" and arrow ("Up" and "Down") buttons on your Carrier thermostat control.
Press and hold down "MODE."
Press both the "Up" and "Down" arrow buttons simultaneously.
Wait a second. The "Locked" icon disappears from the screen. You can now use your Carrier thermostat as normal.