Vilpo

I found a strange problem after replacing a bulb in my auto-ac backlight.. Now the backlight is on constantly, wont turn off when i take out the key even.. Both of the bulbs work fine now though.
I noticed also, that they are at their brightest setting. Instrument cluster backlight works normally and dimmer works for that. Its just the aac backlight thats on all the time.
Any ideas? AAC unit broken or what? Does anybody know how the backlight is controlled, does the signal come from instrument cluster or somewhere else?
Thanks for any help...