I hear you! Or rather, I don't once that stupid fan turns itself on. And you can't shut it off manually once it goes on automatically. Scared the wits out of me too the first time it happened. I should probably take some time and read the owner's manual and see if there's an override or something, but I can't find it . . .

Our GE Profile Advantium in our last house did that as well. I assume that it was is trying to protect itself from overheating.

Thanks for your replies! I read the manual (after this happened) and googled it. There is no way to shut it off. It is so loud. I am not happy with the microwave.

Any over-the-range MW is going to be really really loud. You will not get a quieter exhaust in an OTR MW by buying a different brand. There have been several threads about why OTR MW's are only a good choice if your kitchen is really small and you have absolutely nowheres else to put the MW. Any chance you can switch out the OTR MW for an actual hood, and buy an inexpensive countertop MW (usually less than $100) instead?

Here is a link that might be useful: Thread about OTR MWs

I don't think you understand. It comes automatically. You don't have a choice. It's way loud. Thankfully it's at my Inlaws and now I have another reason not to hear.