Water will corrode your radiator and not good for headgaskets, and maybe that is why you are overheating. The temp for coolant is between 185-195. I also live in Florida. Make sure you have a fan shroud and your fan clutch is still good. If you spin the fan and it spin to quickly or freely then your fan clutch need to be replace. Flush out your radiator and use 50/50 antifreeze. Your heater core could be leaking. And if you want to bypass it you will like need to take the intake platnuim out but if you can get to the hose then it will be a tight one. Your a c will blow could still because heater core is just for heat in the winter time. I'm in pinellas park Florida. If you are close by I can help you at my house. I do all my work on my Z in my garage
