Thanks Guru and Know, I just retested and let it idle about 5 minutes and then took a short ride. Fans went on and off.
No noise, at idle or after the short drive, then idle.

Actually it seems to be operating cooler now. Just a tad above 80 rather than much higher (95) which has been the norm for years (even after new thermostat).

Weird. Maybe a fluke now that I am scrutinizing. (artifact observation)

I will monitor and if needed, will try removing the belt.

Unfortunately, in another thread, my 300SE's fan is hitting some lower pulley.

For sure I need to remove the belt and test the pulleys for wobble motion.

I will update.

__________________
1979 300D 220 K miles
1995 C280 109 K miles
1992 Cadillac Eldorado Touring Coupe 57K miles SOLD
********************
1979 240D 140Kmiles (bought for parents) *SOLD.
SAN FRANCISCO/(*San Diego)
1989 300SE 148 K miles *SOLD