Question(s) about the HVAC unit found in D2 models(two rockers, big display, two rows of 4 buttons)...

First, I notice my display is lit, but the buttons are not. Are those buttons supposed to be illuminated by a backlight?

 

yep...

 

I was afraid of that.

Anyone happen to know if there's a secondary fuse or connection between that particular backlight and other elements of the dash? Clock, HVAC screen, Descent and other switches to the left light... Are those lit via individual elements, or is there some sort of light pipe being used?

 

I'm not at home at the moment but I have an entire control unit taken apart on my desk. I believe there is a total of 5 lights in the unit but will need to double check and see.
3 lights are for the buttons and LCD Display and two are for the Temp control....again I think. I can post more late tonight or in the AM.

But back to your problem. The one was doing pretty much the same thing. So I pulled the lights and test each individually with a 9v battery and two test leads. All worked fine. So I still don't know what causes them not to light up in the Unit. I replaced the unit with a spare I had on hand and they all lit up perfectly. So I know it was not a fuse. Might be a resistor or something in the unit that is blown.

 

That's exactly what I was wondering. It seems really odd to me that only the button lights are out, while the display lights without issue.

If you've got one torn down on a bench, I'd be very interested in what some of those guts look like. Think you might be able to snap a couple pictures of it?

While my buttons don't light, I'm a little hesitant to pull a mostly functional unit apart

Then again, I guess I have to ask myself if it's worth $19.99 for me to replace it(as Classic-Rovers has a unit for that), try and fix it, or just live with it.

 

For $20 I would just replace it. I'll shoot some pictures later and post. There are actually 6 lights. 3 for the LCD 1 for each of the temp buttons and one for the lower row of buttons.