Noisy interior temp sensor fan

[oldskool73]

I have an annoying buzzing sound coming from the passenger airbag area, starts as soon as the key is in the AC on position and when the key is turned to off you can hear it winding down again. I'm assuming it's the fan that draws air over the interior air temp sensor, behind the plastic grill on the passenger dash.

I can't find any guides for removing this, has anyone done it, and/or managed to fix this fan to stop it buzzing? Looks like it's just a small DC fan so should be able to clean and oil it. A replacement is silly money (like $250, for basically a computer fan!)