do the heater control dials light up when your headlights are on?
I had the same issue as you, my dials didn't light up either. read on here you need to replace the light bulbs in the back of the heater control panel, I didn't believe this could work but thought it worth a punt.
£3 and ten minutes later to strip the centre console, new bulbs were in and all my heating and AC working like new.
I got a regulator this afternoon from scrap yard. After getting into some peculiar position to access it - managed to change it - Hey Presto! All ok! About time I had some fortune with this old gal. Have noticed now that only the top half of the speedo lights up - ho hum