My '11 Sierra Denali...a high speed fan comes on all the time regardless of the situation. I can be driving it at low rpms at 35mph and it comes on....I can be driving at 75 on the interstate.....within minutes this morning of a warm-up start in 11F degree temperatures (wtf). I took it to the dealership the other day as it is still under warranty. They said the fan runs as designed. I have a hard time believing that a f'ing fan needs to come on to help cool the coolant when its 11 degrees outside and I started the truck up only 10 minutes prior. Anyone have any idea? I searched the forums and didn't see any relevant info.

In my CTS-V....driving at 140+mph didn't cause any electric fans to come on. Driving at the drag track at 90 degrees ambient didn't cause a fan to activate. Its bothering the **** out me coming on 35 times a day...any advice would be greatly appreciated.

(coolant is 100% at spec level in case anyone has that idea

 

The cooling fan comes on to ensure air flow across the condensor and accessory radiators. If you run your defroster/defogger the AC compressor is in a mandatory ON state, so the high speed fan comes on to keep the system from freezing up.

 

Yes, this...

 

When the fan comes on, turn off your defrost and wait a minute, the fan should turn off. Defrost = ac compressor running= fan on, otherwise your condenser coil will freeze, as stated earlier.