A temperature-controlled fluid friction coupling for intermittently driving a cooling fan of an internal combustion engine. The coupling comprises a drive input shaft having a rotor thereon, a housing rotatably supported on the drive input shaft for supporting a cooling fan, a fixed partition for dividing an interior space of the housing into a torque transmitting chamber and a reservoir chamber, a movable partition for dividing the reservoir chamber into an active chamber and a vacant chamber, a flexible annular diaphragm disposed between the movable partition and the housing, and a temperature sensitive element disposed outside of the housing.Surfaces of the rotor provide shearing surface gaps around the rotor. The temperature sensitive element moves the movable partition in axial directions depending upon a change of ambient temperature thereby changing the distance between the two partitions and controlling a fan revolution speed.