When I start my truck up in the morning or for the first time during the day it seems like the fan is engaged. not really sure how our cooling fans work but it sounds as if it's tied in with the engine rpms. usually lasts for a min or so and then eventually shuts off.

Why would this happen on a cold engine? I could understand if it was 100+ outside but not when it's 40 degrees and the engine is cold.

any explanation?

 

The fan uses a fluid based thermostatic clutch and it takes a couple of minutes for it to sense the temperature and start slipping.

 

hmmm ok thanks

 

I live in Las Vegas and my truck has always done this even when it is 100f+ outside. Usually takes about 20-30 seconds to turn off.