4028 fan speed control reversed

I have encountered a problem with my 4028 fan. The fact that the fan runs at 100% after boot up is known to me. The problem is that the fan only goes off when I set the fan speed to 100%. If I set the fan speed to 0%, the fan runs at full speed. This makes me think that it is reversed. Can I change this in the software or is this a hardware error in my wiring?