Abrupt hissing sound

[crewwolfy]

On my way to work today, the stang started making an abrupt hiss sound every 15 seconds or so. I was trying to feel for any power loss, but I can't say for sure.

I stop the car and pop the hood while the engine's still running. I notice the bottom left (pass. side) pulley (alternator?) is stopped. Then, with a short hiss sound, it starts spinning again. Several seconds later, it stops again with a short hiss.

Can someone help me out on this? I haven't done any mods on the car yet, and it hasn't even reached 3K miles. Any help would be greatly appreciated.

 

[DukeOfValencia]

yeah, several of us have found that. It's just the great engineers at Ford. As far as I've been told it's normal and usually happens when your a/c is on low.
It's annoying, but I'm finally starting to get used to it.

 

[crewwolfy]

Nothing to be worried about then? I guess I'll just pretend my alternator has a BOV or something.

 

[BlackGT05]

I have the exact same problem with my car. I brought it back to the dealer and they said it was normal. It only happens when I run the a/c. It's really a pain in the ass!! I try to avoid using a/c as much as possible

 

[Adrenal]

If it were a common problem to all the Mustangs it would be "normal". I've
had my GT since March 24th, use the a/c a lot and haven't had one hiss.
GTYUP V8

 

[crewwolfy]

I wasn't using the a/c at all when I heard it, I rarely use the a/c at all anyway. But it was much more humid than any other days. I didn't hear it at all on the way to work today. Not sure what that means....but yeah.

 

[bigcat]

i think that powersurge posted that the altenator has a clutch on the pulley....maybe thats it?