During these cold few months I wash quite a few loads using Warm/Warm instead of Hot/Cold for this particular reason. I would like a thermostatic mixing valve for our cold tap water!

What does ATC mean? Only thing I can think of is "All Temperature Cheer" lol.

Automatic Temperature Control ;)

Although our cold is NOWHERE near most of your cold, for the past month our days and nights have been in the 30's to mid 50's. Our tap water is colder than I have felt it in years. It is coming out in the mid to upper 50's from the tap. Not that I would ever wash in cold, but this is too cold for detergents and to shift and remove body oils.

My machine does fill with tap cold, as I set it this way, but the 5000W heater gets to work right away. I wash ALL things between 105 and 150F. Sometimes I will do a 160F, and for fun I have done two 200F loads!

dadoes - was that Kenmore made by Whirlpool? (I see a faint family resemblance to our old toploader)

Surely. Kenmore-branded laundry was primarily sourced from Whirlpool from the 1950s into the 2000s. Later 2000s to current some is from other manufacturers.