Fan Control

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May 16, 2014 | 03:49 PM

ART T

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Staging Lane

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From: St. Petersburg,Fl

Fan Control

I am trying to finish up a lot of little things on my Chevy II before Power Tour. I charged the AC today. I have a single cooling fan that is controlled by the computer. Is there a way to have it come on with the compressor? Thanks

May 16, 2014 | 06:43 PM

gofastwclass

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From: KCMO

If the computer sees / controls the AC, yes.

May 16, 2014 | 09:12 PM

ls1nova71

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From: Liberty, MO

You need a ttrinary switch so the fan comes on with head pressure. If you make it come on with the compressor it will run almost all the time including when running down the freeway which is when you don't need a fan on.

May 17, 2014 | 09:06 AM

ART T

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From: St. Petersburg,Fl

This is how I have the fan wired:

https://ls1tech.com/forums/attachmen...l-img_0240.jpg

I have a trinary switch. How do I connect all of this together?

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May 18, 2014 | 11:16 AM

ls1nova71

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From: Liberty, MO

Quote:

Originally Posted by ART T

This is how I have the fan wired:

https://ls1tech.com/forums/attachmen...l-img_0240.jpg

I have a trinary switch. How do I connect all of this together?

I usually just get another relay and wire it to your trinary switch. Does your switch have 4 wires? 2 blue and 2 green? If so, the green wires hook between the A/C switch on the dash and the compressor, you should already have this hooked up if your air is working. On the blue wires, one will be grounded and the other will go to the second relay, pin #86. Then wire #85 to your ignition source (you can tap off the #85 of the other relay if you want). From there, #87 to your battery source and #30 to the fan just like your other relay. This sounds redundant, but it works without setting a DTC fan code, and in the event your main fan relay craps out, you will have a back up. It's possible to wire the trinary straight to the pin #86 of your first relay, and it will work, but the PCM will not see the relay as it will be essentially wired straight to ground when the trinary switch is closed (path of least resistance) and will set a DTC, and sometimes the code will make the fans come on all the time. Hope this makes sense and helps.

May 18, 2014 | 03:49 PM

ART T

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Staging Lane

Joined: Nov 2012

Posts: 98

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From: St. Petersburg,Fl

I just got in from the garage and that is what I did. I added a second relay, one is controlled by the ecm and the other by the trinary. Seems to work. Thanks for the input.

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