Is it the early or late dash?
Is your A/C button round or rectangle? Round = early
I can check tonight but i am pretty sure on the late dash it has 2 globes in behind it to light it up, so make sure that the connector hasnt come loose. Old dash, I cant remember as I threw that out. Did it just stop working one day or did one side go dull then the rest went?
I just fixed the light in my A/C button. Turned out to be a globe but I broke the switch trying to get it out. $65 later and a 2 week wait now the light works.