Hi everyone this is driving me insane. On my 2002 E320 when I turn on the climate control there is a loud squeal most of the time. It happens more often when the climate control temperature is set higher than the ambient temperature. It never happens when the climate control is set to off. Before it starts making sound I can hear what sounds like an air channel or some part closing. I have replaced the blower motor and regulator two times with known working parts and the sound remains unchanged. I have disconnected the blower motor and the sound remains. I have uploaded a video on YouTube of the noise. The address of that video is:The car has 160,xxx miles. I have searched for hours and hours and spent a lot of money on parts to no avail. Please help.