Fan control? PCM and Toggle switch...

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May 19, 2011 | 12:31 AM

Dave-1970

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Fan control? PCM and Toggle switch...

So I have an LQ9 in a 70 chevelle. My radiator has two electric cooling fans. I have one fan wired up to be controlled by the PCM (low speed) and was contemplating having the second fan operated by a toggle switch on the dash. Should I just have the PCM control both or is there a good reason to have one fan manualy operated??? Thanks in advance!!

May 19, 2011 | 03:50 AM

garys 68

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From: Camdenton, MO

If you have AC, you might consider having the second fan controlled by the AC trinary switch as well as temp. Otherwise the ecu is ok alone for both.

May 19, 2011 | 04:30 AM

itsslow98

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I see no benefit to the switched fan except for being able to turn it on when the car is off.

May 19, 2011 | 09:20 AM

Agent_Orange_Shuvel

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If you plan on drag racing it much the toggle switch isn't a bad idea because you can leave the fan on while waiting in the staging lanes. Otherwise running both of them off the PCM works great.

May 22, 2011 | 03:22 PM

LS88FoxBody

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From: Demotte , IN

Quote:

Originally Posted by Agent_Orange_Shuvel

If you plan on drag racing it much the toggle switch isn't a bad idea because you can leave the fan on while waiting in the staging lanes. Otherwise running both of them off the PCM works great.

I was going to just do switch controlled. But Computer controlled will be nice. Problem is making the normal switch work while switching ground too...

May 23, 2011 | 05:07 AM

2xLS3

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Quote:

Originally Posted by LS88FoxBody

I was going to just do switch controlled. But Computer controlled will be nice. Problem is making the normal switch work while switching ground too...

Just use another relay with the contacts in parellel of the one controlled by the PCM, then run a switch to one side on the coil and ground the other side

May 23, 2011 | 09:18 AM

Dave-1970

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Thanks for the replies!! The car won't see the track too much and I would hate to leave it on and forget about it so I'm going to let the pcm do all the work...