Just bought an 06 300c and it has no heat, it also will not switch between modes. It is stuck on blowing cold air through the vents. When I turn the knob to try and go to floor or defrost nothing happens. There is no clicking, knocking sound in the dash, or any other sound. I'm in the process of pulling the dash off but I really don't want to do that if someone has a suggestion to try before I go through all that.