Mild buzzing sound from the climate system

[nexion]

A mild buzzing sound comes on when the climate control system is set to blow either at the windshield or the feet and tends to go away when set to blow around the middle. It's still present when fan speed is 3+, but the other wind noise dominates it at that level, so it's fairly subtle. Easiest to hear it on fan speed 1. Tried recording it with my phone, but it didn't pick it up as it's quite subtle. It sounds like some fan may be defective and is scratching during rotation.

Wondering if anyone else had a similar problem and what the diagnosis and/or fix was.

 

[nexion]

Ohh, I found an easy way to reproduce the problem. It seems that the buzzing sound is on regularly when the climate system is heating, but if I set the desired temperature to be colder, the noise instantly stops. It appears to be caused by the car trying to warm up the cabin. Note that the fan speed is set to the same (speed 1) in both cases as the climate system is in manual mode with the only thing I'm changing behind the set temperature.

I'll compare this to my friend's M3D as well to get an idea of whether or not this is a defect or if I'm just being overly picky.