What temperature does the thermoswitch open? It should be indicated/etched on the side or something. That way you know what to expect when the coolant temp reaches that temp (fans should start).

Agree on replacing thermostat. Get one that's set lower than factory. If it says it opens at a certain temperature, it means it just starts to open at that temperature, but the operating temperature of the car will be higher since the thermostat is only rated to open at that temp. It will be fully open a few degrees higher.