It's most likely the rheostat control that adjusts the fan speed. When they are going bad they only run at full speed. On my RRC it is a real chore to get to.
From my research, it looks like it's behind the glove box in the Disco 2.OP has a Disco2 if it makes a difference?
From my research, it looks like it's behind the glove box in the Disco 2.