Why is the car electronic fan replaced so fast

In the process of repairing the locomotive, I heard such a sentence, 'I have changed four or five electronic fans. Give me a good quality one.' During the period, I was puzzled. Isn't the service life of the electronic fan relatively long? Why have it changed several times? Is it man-made? Based on this situation, I have made the following thoughts. The significance of the existence of automotive electronic fans is not to reduce the temperature of the water tank, are there other uses? After thinking about it, I still didn't think of a better answer, so I didn't think about this question. Later, I thought, could it be that the heat dissipation speed of the electronic fan was not adjusted according to the product requirements? But later, such a problem was rejected by myself. the reason is simple. The operating speed of the electronic fan can be regulated. If you want to operate in a low-speed mode, you only need to connect two resistors in series on it. If it is operated in a high-speed mode, there is no such trouble.