I think people weren't sure what exactly you were asking. The engine fan thermo switch should be rated above the engine thermostat temp rating. So your fans don't come on until there is water going to the rad! Try an 88C engine thermostat and a fan thermostat switch around 92C. Many front wheel drive cars should run at about this temp so you should have no probs sourcing one. Just remember modern cars run the fan from the ECU so you would be looking around the late 80's when ECU's were primitive.

