Carrier KJR-120C/TF-E Manuel D'utilisation page 21

9. OPERATION
Child lock function
°C & °F scale selection (on some models)
Press and hold "+" and "-" buttons together for 3 seconds
or more to activate the child lock function and lock all buttons
on the wire controller.
Press the buttons again for 3 seconds or more to deactivate
the child lock function.
When the child lock function is activated,the
Press and hold
for 3 seconds will alternate the temperature display
between the ℃&℉ scale.
18
and buttons together
G B
mark appears.