Our Ac controller display went dead. We had to replace the bulb and this is how we did ours.
We need to remove the face plate and the control unit out to replace the bulb(s) in the back of the controller. Pry the left and right sides of the wooden plate slowly and carefully.
There will be a hex bolt on each side that need to be removed to take out the controller.
We changed our using Orange base = 1.1 w makes the display brighter.
Put back everything in and the AC controller is bright and good as new.
Cheers,