Loud fan like noise- trans going?

My 2000 Forester with 150000 miles is running fine but when driving it sounds like a fan is running too high- this sound happens whether the air/heater is on or off. One mechanic said it could me my transmission going-- but my car is manual. When idling, it does not make the noise.

What kind of cooling fan does this vehicle have??

If it’s mechanical then it probably has a clutch. If the clutch is bad it could make this sound.

I don’t know the kind of cooling fan but it does have a clutch.

That is NOT the same clutch I’m talking about.

Anyone know this vehicle to help the OP out.