I installed a new radiator and a new ECT switch (sensor) and filled the radiator with fresh new coolant.
I ran the engine for approx. 15-20 minutes and even drove around the block, but the radiator fans never turned on. It didn't overheat though and the needle on the dashboard never went above half-way. When I disconnect the connector on the drivers side fan that connects to the ECT switch on the bottom of the radiator, the fans work.