You need to be careful in the type of paint you use. The raised letters you describe are also lighted in the same circut as the dash and instrument lights. If you paint them with the wrong paint or too heavy, they will not glow at night. Some paints, even white, have ultra fine particles of
metal in them and are not transparent. They are painted white at the factory; possibly with the same type of paint used to frost outdoor Christmas lights? I don't know. Try it on a small spot first (the tiny dots on the fan speed control) before painting all the letters. Let the paint dry and see if they still light up in the dark when you turn your headlights on.Find out if the plastic pieces can be removed from the bezel---they appear to me to be seperate parts, but I could be wrong. Then dampen a piece of paper with the paint on a flat surface and stamp the plastic pieces on the wet paper. Only the highest flats of the letters will get the paint. If you can not remove the lettered pieces from the bezel, then I guess you will have to find a very small brush and a very steady hand.Good Luck!
