Radiator fan always spinning

[Trailblaster]

I didn’t realize til recently that the cooling fan(mechanical belt driven) is always spinning on my 22’ HD gas engine. It doesn’t look like it has a fan clutch. Is this normal. It’s already hit temps in the 20’s and   In previous trucks, they were electronic or had a clutch.

[Pryme]

The clutch will slow it down so it’s not turning at engine speed unless it needs to. I’m sure it’s working as designed.  

[newdude]

57 minutes ago, Trailblaster said:

I didn’t realize til recently that the cooling fan(mechanical belt driven) is always spinning on my 22’ HD gas engine. It doesn’t look like it has a fan clutch. Is this normal. It’s already hit temps in the 20’s and   In previous trucks, they were electronic or had a clutch.

 

 

Normal.  They still have a fan clutch.  Fan spins regardless (still needed for normal cooling system operation and for AC condenser airflow at low speeds/parked). 

 

The fan clutch in gas HD uses a bi-metallic spring that expands and contracts based on a set temperature.  As the spring changes position is adjusts a control valve and moves the fluid inside to then modulate the torque applied by the clutch.  

 

Diesel uses an electro-viscous fan clutch.  

Edited November 9, 2022 by newdude