I had a similar problem with my defrost. Mine wouldn't switch between the different levels, so all I had was defrost. Took it to the dealership and had a vaccum issue. This might not be the issue your having but its a start..
2" Rubicon Express BB,1" BL, 33/12.50/15 PRO COMP M/T's and 15x8 Cragar soft 8's
Pioneer head unit, audiobahn 800 w amp. 12" Brutus carbon fiber subwoofer