I know I am in the minority here by far but I am red/green color blind. I see colors but some shades that are similar I cannot distinguish. For example the red and green LEDs on Orion. They are used everywhere and unless the word down or up is somewhere around I cannot always tell the difference.
I would imagine for people whom are fully colorblind it is that much harder.
My suggestion would be to always accompany an LED with the words UP/DOWN/WARNING as part of the graphic.