I run my Perma-Cool fans by using the temp. probe pushed in the radiator that they supplied with the kit.It tells the fans when to go on and off by the temp. of the radiator.The fans also have a wire that can be hooked up to my AC to turn them on and off.I've not hooked that wire to my AC.

My ? is can I use the AC wire off of the fans and hook it to my PCM [I think it is #42 on the blue side] and have the PCM control when the fans go on and off?

I know my tuner would have to turn that option on and this would eliminate the temp. probe.

 

It depends if the supplied ac wire uses a positive or negative trigger, the PCM grounds pin 42, so if the ac wire uses a negative trigger you're golden. If not, you could always wire in a relay (or re-wire the supplied relay if it uses one) to allow the PCM to ground that pin. I'm assuming that the temp probe is a 2 wire or something and can't just be cut out of the system and it's wiring tapped into the PCM?

 

hmmm....never thought of running the Ac wire to the PCM...

i also have the permacool fans, but had them send me the threaded thermcouple...unfortunately, it is for SBC heads, not LS stuf. A friend of mine machined me a piece of hex brass to make a head probe and it works. however, the fan kicks on after i shut down the truck because the adapter piece sticks out about .75 inch from the head and triggers off the heat from the headers.

i ran my blue AC tire to a dash switch as an override becasue the thermal probe that came with the kit NEVER worked.

Be nice to set it up so they go on with single or dual stage as cooling demand increases.

-patrick

 

If I just ground the blue AC wire and the fans come on I know it is a negative trigger?

 

That will work, but I believe the A/C wire needs a positive trigger. Easy enough to check though.

 

If its like any other thermostat controller ive used the AC is a Positive wire...
So your goin to have to put a relay on that wire if you want to run it to your PCM, which is a Grounding Pin..

 

So if grounding it does not turn the fans on, could I touch it to my pos. on my battery to see if it is a pos. trigger?

thanks for the help