DanielJ

This all started a couple weeks ago. Noticed that with the key off or with key removed, there is a slight buzzing noise coming from somewhere inside the dash. Pulling the #1 spade fuse (Heater/Fan), the problem (noise) goes away. Also noted that once the spade fuse is replaced, no noise, but once the key is cycled, the noise comes back and is persistent until the fuse is removed. Some relay in there go sideways? Other guesses or ID of the issue?

Thank you all for your help.

DanielJ

Deserion

Could be the CCU fan.

Vegas993

Yes, likely your CCU fan. It will shut off after a few minutes. There is a DIY fix around here somewhere.

cjoenck

Yes, most likely.

ToreB

The CCU fan runs for up to 20 minutes after ignition off. This is done to ensure that the cabin temperature is correctly sampled after short stops such as at a gas station.

The fan motor wears and will start making whirring and rattle noise, and will eventually stop due to motor failure. A non-op CCU fan will severely impact cabin temperature regulation.
Cheers,
Tore