Tank humidity to high?!?

I put down some new substrate in my crested geckos tank, exo terra plantation soil, it's been in there for about 2 days. the stuff is sort of damp and moist, since I put it in the tank, the humidity has been way to high, I've turned on the air conditioner,which helped a little, but the humidity went back up! I have to spray the tank so my gecko will drink.. what do I do? the humidity should be about 70%. it's like 90!%