Funny you should mention this. Not three weeks ago, I had to replace the little bulbs in my seat heater switches that light up the seat icons. I ordered two of each from my local dealer because neither of us could tell from the drawing in his illustrated parts breakdown which bulb was for which function. Total cost to order the four bulbs was around US $24 (your price may vary). I don't know if the same part numbers are used in the rear defroster switch.
The bulbs for the seat icons:
Part # 18691-08041 (black base)
The bulbs for the amber "on" indicator:
Part # 18691-05041 (gray base)
If you need any pointers on removing the center console, then the subassembly holding the switches, then the switches themselves, that memory is fresh. Let me know if you need a how-to on that.