I can smell fuel when I have my fan on in my MK4 Volkswagen Golf. My air conditioning unit packed up about 12 months ago which didn't bother me, but was expensive to fix so I left it.

But during the hot weather I have used just my fan to circulate air around the car and after about 10 minutes or so, you can smell a slight hint of fuel coming through the fan, just enough to be unpleasant.

My dad said even though the AC doesn't work have you tried putting just the button on to see if that helps. So I did and the fuel smell did appear still but it took longer to come through - about 20 minutes - which is better but still unpleasant on long drives.