Heater fans inside car
 

Does anyone else get a squeak all the time from the heaters/fans inside the cabin? Any ideas how to fit it???

There's one fan assembly in the cabin and I've never heard one squeak before. If yours is actually squeaking then you should changed the whole assembly out

I'm going to take a guess and say that the squeaking noise is the main bearing in the fan (that is wearing out).

Replacing the fan in my e60 is a full day job.

Definitely an all day affair. Did it about 8 years ago and will never do that again.

I paid BMW to do mine. Only because my time would have costed me much more.

I have a similar but intermittent noise on the ventilation fan on my 2007 530i. I do my best to tolerate the noise and play with the controls until I can get it to subside. For me it's not worth tearing apart the entire dashboard area to try and fix it. But yours may be worse and/or your tolerance for that aggravation may be less and you'll want to fix it; if so best of luck.