strange noise in XPS 15z when a fan reaches 0RPMs

I have a problem with the fan in my Dell XPS 15z machine ...

Whenever it turns off (reaches 0 RPMs) after couple of seconds I've got very strange noise, like if some metal would hit another metal (to be more specific it sounds like farting - seriously)...

First time it happened after few days of using computer when technician changed the cooling system because the fan was constantly on (got it refurbished & 1st fan I had was never calming down - that's why I called them to change it)...
In the meantime I had some other problems with the XPS 15z (system freezes) so they changed my motherboard...

After I called and request the new cooling system as the 2nd one seemed to got broken (same issue as now = strange noise) they replaced it for me and after 3(ish) days I got the same problem again (on my 3rd cooling system, the current one I have)... strange "farting" noise every time fan goes from "any>1"RPMs to 0RPMs state...

What should I do? Of course I can call Dell and request another replace of fan and heat-sinks but what causes this issue... :|
I would also risk to say that the noise gets louder and louder every day...
Could I be just unlucky getting 3rd faulty cooling system in row? Or maybe there is something different that is the problem here... I checked when the technician was changing the fan - there is nothing that fan's "wings" could possibly be in contact with... neither in the "new" one he was putting nor on the "old" one...

looking forward your suggestions and tips...

 

I would just opt for a new fan replacement and pray that no more will come of it.

IMHO the fan sounds as if it is suffering some bad vibration when it is at a very low speed (so slowing down just before it physically stops completely). - correct me if it sounds different

It also wouldn't do much harm to double-check with a bright light that nothing is obstructing the vents/fan.

My XPS 15 had a similar problem where the fan would making that noise ALL THE TIME It sounded a bit like the bearings were worn or a metallic grinding.
It required two replacements before the problem was fixed

 

I had the same issue. Dell sent me a new fan to replace it with, and that resolved the issue. It's definitely a defective fan.

 

all right, thank you guys, will call Dell soon about one more fan replacement

 

Hi there,
I have the same exact problem: a fart-like noise when the fan slows down to 0 RPM. What did Dell say about it? Has replacing the fan solved the problem? Thanks

 

Yes, I called them and without any problems they sent a technician to replace the fan for another one and it worked!

sorry for a late reply...