I turned on the heater, I tried to turn the heat down. it was stuck on the heater. Itried to switch it to the AC,the defroster,thermastat up or down! Nothing happened, it was stuck on the heater. Itried to turn the truck off,. it still would'nt shut off . Ihad to diconnect the battery to shut it off . Then I reconnected the battery,. And then the ac-heater would'nt even come on !!!!! Ziltch.?????? HELP.