The following reasons will make the automobile electronic fan turn all the time: 1. Insufficient cooling water: cause the engine to overheat and the electronic fan runs continuously. 2. Water leakage in the water tank: the engine is overheated, the rubber hose is loose or damaged, resulting in water leakage, and the electronic fan runs continuously. 3. Thermostat failure: due to the thermostat, the temperature reaches the reference temperature, and it is impossible to send water to the water tank, or the water supply is too small, resulting in overheating of the engine and continuous operation of the electronic fan. Extended data: the current household car water temperature cooling fans are all electronic fans. The electronic fans have two gears and are controlled by electronic temperature controller. When the water temperature exceeds 85 ℃, the fan will continue to operate at low gear. If the water temperature continues to rise and exceeds 95 ℃, the fan will run at high speed and force heat dissipation. The fan will not stop until the water temperature is lower than 85 ℃. The whole car fan is electronically controlled.