Radiator fan runs when engine is cold

If the computer decides to, my electric fans run during remote start. GMT900s.

The conventional clutch fan on the 900s flows more air than two 700 watt electric fans. Don't recall how much anymore.

swathdiver said:

The conventional clutch fan on the 900s flows more air than two 700 watt electric fans.

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Over as little as 1000 engine RpM, I'd be willing to bet that that's true.
If I were in the market for a GMT900, my only questions would be:
Does the mech fan flow more air than two OE electric fans AT ENGINE IDLE?
Is it enough for the AC to continue to perform well at idle even while stopped in traffic @ 45C / 113F outside?

Just noticed you said 'two 700 watt electric fans'.
Guessing those are NOT OE for GMT900s?

Marky Dissod said:

Over as little as 1000 engine RpM, I'd be willing to bet that that's true.
If I were in the market for a GMT900, my only questions would be:
Does the mech fan flow more air than two OE electric fans AT ENGINE IDLE?
Is it enough for the AC to continue to perform well at idle even while stopped in traffic @ 45C / 113F outside?

Just noticed you said 'two 700 watt electric fans'.
Guessing those are NOT OE for GMT900s?

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Many GMT900s come factory equipped with 700 watt cooling fans. All three of my trucks have them.

I don't have a 2500 Suburban or Yukon XL, those have a mechanical clutch fan. Let's ask a few. @Derick @intheburbs @Moosemoon

Some more who might share their experiences:

@Jimmit @Shackman7878 @Nap73 @99bluefirebird @Oldmopars @t_bergman @tungsten @02Yukon2500 @S33k3r @Goober @DRayson @YukonBrian

swathdiver said:

If the computer decides to, my electric fans run during remote start. GMT900s.

The conventional clutch fan on the 900s flows more air than two 700 watt electric fans. Don't recall how much anymore.

Click to expand...

The 900s come with clutch fans? I thought they were all electric for NNBS.

Fless said:

The 900s come with clutch fans? I thought they were all electric for NNBS.

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The 2500 SUVs at least. The 6.0s in the HD pickups might have them too. Not sure what the Duramax's have.

swathdiver said:

The 2500 SUVs at least. The 6.0s in the HD pickups might have them too. Not sure what the Duramax's have.

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Yup.. I do miss the jet engine take off under 30mph on a morning start. Kinda miss that noise. Sounded manly. 15 mph, 2nd gear driving through the neighborhood ... THRUSTERS AT FULL!!!

Any 6.0 or Duramax Ive owned are clutch.

swathdiver said:

Some more who might share their experiences:

@Jimmit @Shackman7878 @Nap73 @99bluefirebird @Oldmopars @t_bergman @tungsten @02Yukon2500 @S33k3r @Goober @DRayson @YukonBrian

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I have a 09 Yukon XL (gmt900) was thinking about ditching the clutch fan but cant find a decent kit or write up that dose not involve reprogramming something after or having to new temp switch, or something you stick in the radiator. I noticed it sounds like a jet engine in the morning until the engine warms up.

Video on how much power it robs -

Based on my preliminary experience with the e-fan conversion here are my thoughts, with more to come as we ramp into Texas summer:

Idle/low speed AC performance: Electric fans
Highway (55+) AC performance: Mechanical fan
Butt-o-meter (SOTP) go-fast: Electric fans

As I did the programming to turn the e-fans on, I know that I used to stock setting of 45MPH to turn the fans off, so it reasons that the highway performance is better with a spinning mech fan. Hopefully that's the case, or I'm facing more AC repairs. It used to freeze my face off. Now it's just "cool". I think I measured high 40's at the vent.

I still think I'm ok with this trade-off if it is legitimate, because idle/traffic speeds AC performance have always been less than desired. I'll report back when we get hotter and I drive it more...I'm still not driving much at all.