I have begun experiencing this problem recently since it has gotten colder out. After the car warms up, at around 2300rpm a very loud whining noise begins coming from the area around the climate control unit. My e24 has the older-style layout, and when the temperature selector knob is turned to the high-heat/defog setting the sound goes away. Any thoughts? I posted a video of the issue below.
No the noise remains the same regardless of fan/blower speed. The air flow knob does not affect the sound either, but that knob is stuck (posted in a previous thread but has been addressed). However, I did not mention this earlier but I have noticed that there is a bit of resistance in turning the knob before the sound goes away. It feels as if there is like a threshold you have to "break through" before continuing to turn the knob, after which there is no more resistance. UPDATE: The knob resistance has something to do with the cigarette lighter, but has no affect on the noise itself when the stopping problem is removed.
So when you adjust the temp knob to hot the noise goes away correct, but is there from cold to almost full hot?
That is correct, from about 3/4 heat to full heat the sound goes away, however the sound is there at any other temperature below 3/4 whether off or on A/C.
I get a whining noise too when I have the heat turned down, usually it's my wife complaining that she is cold.
Sounds like your heat blower motor is making the noise would be my best guess. In your vehicle there are two blower fans one for A/C and one for heat. As you adjust the temp it will decide which fan to turn on. I would look into the fan.
