... after over 2 hours of fiddling around with the air control illumination, all I can say is: save yourself the work, without a different overlay there's no point in putting LEDs in there (except maybe for the heat/power savings).
Not knowing how to get them freakin' light bulb sockets apart it's a major PITA ... I know now ...
Also, don't even think about taking out the panel piece for the heater - the temperature selection knob/assembly is hard-wired to the air intake ... you'd have to unscrew the whole knob assembly to get the rest of the panel out ... (or cut the wire ...
)