well. my heater was working fine. this morning. it was cold and i had to turn the heater on, but it didnt work. you know in my sentra i got 4 levels. 1,2,3 dont work. only 4 worked. which is really strong and hot. the same thing for the ac. i have 2 choices. either OFF or at 4. u guys have any clue why 1,2,3 not working? thanx for ur time.