A thermostat will open and close at the same temp, it?s controlled by wax and a spring, it?s not variable but will have a max opening or valve lift as it?s called which is usually 8mm and is reached when the temperature is around 95 ish. Even the ones that aren?t wax they will still open and close at the same temp, that?s what they are designed to do. The actual fan will shut off at usually 5 degrees below it?s on temp, so if it?s coming on at 101 it will go off at 95 ish.