When i drive my 1994 chevy s-10 Z engine truck i sometimes get a loud spinning sound. It doesn't do it all the time. It sounds like its coming from the engine. I have NO check engine light at all.

I'm from Wisconsin and its only been doing this for the past couple of weeks. The average daily temp right now is in the 20s.

Ive tried to look it up online and found really nothing. Somethings that come to mind might be the fan clutch, drive shaft spinning fast, bad exhaust, bad bearings somewhere or just its cold outside and its trying to keep my truck warm .

If someone can help me out with this that would be great.

Thank You
Brian