My Disco II used to do similar things..
What I would do then I would reset the climate control by switching to C and back to F
One could do it by:
Turn the ignition on.
With the climate control turned on, push and hold the recirculation button in. While holding the button in, push and hold the off button in for 3 seconds or until you hear a beep.
The display should then change to “F”. Follow these same steps to change your read-out to Celsius , if preferred.
Then all would go back to norm