# Electric Cooling Fan Info

**URL:** <https://community.cartalk.com/t/electric-cooling-fan-info/4570>\
**Category:** Maintenance/Repairs\
**Created:** [September 14, 2007, 12:03am UTC](https://community.cartalk.com/t/electric-cooling-fan-info/4570 "2007-09-14T00:03:08Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![goldie](https://avatars.discourse-cdn.com/v4/letter/g/e36b37/32.png) [@goldie](https://community.cartalk.com/u/goldie)\
**Post date:** [September 14, 2007, 12:03am UTC](https://community.cartalk.com/t/electric-cooling-fan-info/4570/1 "2007-09-14T00:03:08Z")

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My vehicle is a 07 GMC Sierra. It has twin electric fans for cooling the radiator. My questions are:  
  
 1. Do they both come on at the same time and at what temperature (approximately)?  
  
 2. Does one fan start before the other and at approximately what temperature?  
  
 3. Where can I find a wiring diagram for the fan circuit(s)?

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<div class="post-metadata">

**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [September 14, 2007, 12:29am UTC](https://community.cartalk.com/t/electric-cooling-fan-info/4570/2 "2007-09-14T00:29:08Z")

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[b]The fans work in this manner.

When the coolant temp reaches about 220 degrees, only the primary fan turns on.

If the AC is turned on, both the primary and secondary fans turn on.

If you want to see how this circuit works, go to your local library and on the computers you can access the ALLDATA data source. If your truck is too new for the information, just go back a year or so until you find the most up-to-date vehicle. The circuits still work the same.

Tester[/b]