Okay I just recently upgraded my cooling system with a new fan switch and thermostat. I have a Summit 180* Thermostat. And a Hypertech fan switch that is supposed to turn on at 200* and off at 185*. The problem is that the fan and thermostat both activate at around the same time.

Also, they both turn on when the temp gauge is on the middle mark between 100 and 220.

 

I was having the same problem after installing elec. fans from a '89 camaro to my '84 T/A. The parts guy told me about PAINLESS WIRE'S adjustable fan control cost me like $60 bucks and u can adjust when the fans turn off and on with a flat head screw driver it's GGGGGGGGGreat

 

there is also a reostat control that alows you to control when the fan turns on and off with the temp. it not wired into the temp sender though. It alows for like highway driving the fan not to turn on but when sitting it does. it works i have used on before.