Saturday I turned on the AC and heard a loud grumbling from the front end. I gathered it was from the AC cooling fan behind the radiator. Since I was on the way to a wedding, I just turned off the AC and no more noise.
Sunday I took a look and didn't see anything wrong, other than the broken belly pan cover, (which I fixed) and with the fan on, a lot of vibration and subsequent noise. I tried flexing the plastic to make sure it wasn't hitting anything and it isn't. Just a vibration. After running for about 1/2 hour, it seems to have settled down. Maybe just a dry bearing in the fan from not being used all winter??
Engine temp never got above 192, and usually was around 188, same as always.never noticed the noise when the temp cooling fan comes on, not that it does too often.