Ventilation again (power)

Hi all, I got my v70I (year 96) three years ago in December. short time Later (January) my fan got off and I quickly bought and installed one at Polar Parts. At that time I didn’t know this forum or vehicle parts Albert 😉 and it had to go fast because we had only one car. This year we have a second car (a 12 year old golf), whose heating keeps the windows free without any problems, while with my elk the heating has to run on full gas! I can’t imagine that this was so from the beginning! Can that be that the cheap fans also have less power?