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Output to control an intercooler fan

Paul Moran

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My new set up has a fan on the intercooler.  After reviewing the (old) LinkPlus manual, it looks like I could control this through the Drive A, the Drive B or the Water Spray outputs with a relay between the fan and the output.  Drive A and B can switch based on RPM or %FF while Spray can be based on %FF or MAP.  I would assume Map over 100 KPa (or some KPa over 100) would be the simplest setting so the fan is fully on as boost rises while its off under any vacuum. 

Is there a preferred output and configuration to control an intercooler fan?


PS. My new Bosch IAT sensor (part # recommended on this forum) read perfectly when I hooked it up last night.  I hope to get a chance to do a test drive tonight...

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The fans a hard one, you really want it to come on when IAT exceeds a certain value, then go off when it goes below that value.  The problem with switching it on under boost is heat soak.  The intercooler will get hot, then when you come off boost the fan will switch off and the intercooler will remain hot for some time.  If the fan keeps going, it will cool the intercooler faster...  Unfortuneately there is no one here to ask at the moment (I am only really involved in G2/G3 ECU's), but check that the IC spray drive does not pulse or PWM.

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  • 3 weeks later...

Hi Ashley - Just wanted to check in again to see if anyone else was there to ask about the intercooler control.

Your heat soak issue makes a lot of sense.  Having the intercooler stay hot from the last boost would not be a good think.  If the fan was controlled by MAP, and MAP dropped below 100 KPA, I would think the air flowing inside the intercooler would be close to the ambient air temp (no pressure, no change in temperature?).  Would this then cool the intercooler back down pretty quickly by just using the air flowing through the inside of the intercooler?

I wonder if I could use a relay with a capacitor and resistor set up to latch the fan on for a number of seconds after the boost drops off.  This way the fan would stay on say for a minimum of 10 seconds after boost disappears thus allowing the left over heat to be removed from the intercooler.  Seems like it would be simple enough to wire up and using a variable resistor, I could adjust the hold time when the LinkPlus shuts off the Fan-On signal.

Thanks, Paul..

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You would need a few more components than a resistor and capacitor, but the theroy is there...  The airflow through the intercooler when the throttle is closed is almost non existent.  Remeber all that can flow is what can squeze round the throttle plate and through the ISC air bleed...  I would fit a thermo switch to the intercooler and use that maybe in conjunction with the ECU to contol the fan...

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