I like 180. Colder is not automatically better. If it were, we'd just leave out the thermostat and run as cold as possible. An aluminium housing is a nessessary upgrade as well. Save a little bit of weight, doesn't rust, and no galvanic corrosion.
On your coolant, since you're in FL, I'd do RMI and water. As long as you keep an eye out for random global warming cold snaps that get to below freezing.
I started at the first one closest to firewall pulling them checking to see if went off finally when I got to the last one closest to front of the car it turned it off so is that the one that is bad it says that one isn't controlled by ecm
I don't ever run the ac bc it runs like a dog with the ac on there are three coolant sensors the idiot one on turbo side front of motor
and the one on front of motor controlled by ecm drivers side think that's the override one and the one on top of intake drivers side
I eventually want to replace them all because of age
is it the high pressure switch or low pressure switch on ac that would also cause the fan to run and which coolant which to check first