Low-blade-frequency noise automobile cooling fan and control method

The invention discloses a low-blade-frequency noise automobile cooling fan and a control method. The low-blade-frequency noise automobile cooling fan comprises fan blades, a motor, a flow guide ring, a fan fixing framework and a wind protection frame. The fan blades are fixed on a bearing of the motor, and the motor drives the fan blades to rotate after being electrified; the tail ends of the fan blades are connected with the flow guide ring; a wind protection frame is mounted between the flow guide ring and the fan fixing framework; the gap between the wind protection frame and the flow guide ring and the height of the wind protection frame are adjusted, so that the vortex effect at the blade tip of the air inlet of the fan is reduced, and noise of the fan is restrained. The air protection frame is additionally arranged between the fan flow guide ring and the fan fixing framework, meanwhile, the gap between the air protection frame and the flow guide ring is adjusted, the height of the air protection frame i