I've got a 2000 coupe I've had for 17 years and over a hundred thousand miles. For the third time I recently had to replace the bulbs in the HVAC head unit. Not easy, and afterwards one has to check that all still work. The one thing that didn't light up was the rear window defroster- LED. The last time I did this, like 10 years ago I think I remember having the same issue, but later in colder weather when I needed the defogger to work it did- and the LED on the HVAC console did light up. After a long internet search and reaching out on 3 Corvette forums, I found only one thread where another C5 owner thought in the back of his mind that the light would not go on in too warm a temperature, or when it's not needed.

Could some of my fellow C5 owners simply go to their cars, turn them on, and try to put on your rear defroster? Also, when you do it, what was the approximate temperature in your neck of the woods? That's all I'm asking, and post back your results. Thanks a million!

Yours,
Bluemill

2000 Navy Blue coupe, black interior, 124K miles, Z06 exhaust, 6 speed, Zip tie air cleaner Mod, smoothed intake-throttle body throat, cold air cut out panels in fog light bulkhead, HUD, C6 short throw shifter.

 

If the rear defroster terminals are not too hard to get to then you could check to see if the voltage is getting there when the LED is not on but you have selected the rear defroster.