[Jim@HiTek]

Originally Posted by fdryer

^ In a nutshell, heater control malfunctions occur can occur in these areas; wiring, control head if its auto climate control (no cables, linkages to control panel), hvac internal door mechanism and actuators.

Are there any tests to narrow it down? BTW, I don't hear any funny noises inside the cabin when I change functions with the electronic climate controls. I changed the paper cabin filter not long ago and didn't see anything strange or broken inside there either.

I haven't tried to take that inside area apart yet.