My wife's Peugeot 604 Turbodiesel had a 12 blade fan that worked off a magnetic clutch. This was the primary fan. The secondary fan is a 25 amp electic (13 blades). The primary fan and clutch self destructed and I removed all signs of its existance. I wired the the secondary electric fan into the primary thermostat and I've never had a cooling problem using the secondary fan as the primary.