Arthur,
I jumped in a few posts back because I live near Ismalley and feel his pain. I had Jim F. make a special resistor that comes on at 88C and off at 82C. This keeps my engine temp just below 100C even at 115F ambient. Long ago I switched coolant ratios and use only a gallon of antifreeze, balance distilled H2O and "Water Wetter". Since I will never experience freezing temps, this is ideal.

While these things keep th engine cooler, I have noticed that in temps over 105F, the AC cabin temps climb. I use a thermometer in the center vent. While the cooled air is a lot cooler than the outside air, I no longer get 40F coming out of the vents. I have resigned myself to these facts. We try to run our errands in the AM before we hit 105+
Anziani
'93 300CE
'95 E420