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Discussion Starter · #1 ·
Hello folks,
I'm wanting to add a fan to my intercooler on my car, but I don't want it to be on constantly.

Ideally, it would be somehow wired into the IAT (Intake Air Temperature) sensor and only come on when temps go above a certain point like 95 degrees. Then there would be an override switch inside the car that would normally be on that I could turn the fan off at my discretion.

The problem is that I am not sure how to do the IATemperature-dependent switching. I'm assuming it is a 0-5V sensor and temps correspond to voltages, though I don't know at what that correlation is. Any ideas?
 

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It would probably be the easiest to find yourself a thermal switch set at 95, or an adjustable thermostat, and install it into your intake. Trying to tap into the cars wiring is likely to open a can of worms.

You could measure the voltages, you'd then need a voltage controlled switch to turn on your fan.

Your vehicle manufacturer may publish the specs in their service manuals, or you can test it yourself.
 

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Discussion Starter · #3 ·
It would probably be the easiest to find yourself a thermal switch set at 95, or an adjustable thermostat, and install it into your intake. Trying to tap into the cars wiring is likely to open a can of worms.

You could measure the voltages, you'd then need a voltage controlled switch to turn on your fan.

Your vehicle manufacturer may publish the specs in their service manuals, or you can test it yourself.

I could nick the IAT wire and get the voltage reading while seeing what my SCT OBD scanner says for temperature at the same time... get a few readings at different temps/voltages and map out a correlation.

So for example if I find that the temp is 90 degrees at 2V, and I want my fan to turn on at that temperature and higher, do they make voltage switches set at different voltages then? Like in this case a 2V and higher = ON switch?
 

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Just be careful with the sensor wiring; if you put any load on the sensor signal wire, you'll at least screw up the reading and quite possibly toast the ECM's A/D converter. If it were me I probably would try to use a separate temperature sensor. If I were going to tap the IAT signal, I'd definitely build the voltage-triggered circuit and the fan control circuit separately, with an optoisolater in between.
 

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There's a good chance the existing sensor is not analog. It may be I2C, 1-wire, SCI, or even CAN-bus. Analog sensors have been out of favor for quite some time now. Either way, it will be far easier and cheaper to use your own thermal switch.
 

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" Euro " electrician
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Intercooler as in a turbo intercooler? If so, why would you want to use a fan?
I belive the OP want to have a fan to keep the intercooler cooled off a bit in slow speed operation.

To the OP the best soluation is have wired up a seperated thermosat sensor for the electrique fan plus what more you may have to find a pusher verison instead of puller { standard format } fan arrangement.

I have no electique fan in my truck due have electromagatic clutch to kick on the fan { it is pretty huge 30 inch 7 blade hi flowage verison } when it kick on you can hear and feel the viberation so you know it is on.

{ it wired up so the following items will kick the fan on ., semi high coolant tempture , A/C compessour. and of course during engine brake mode I turn it on manually that worth about 40+ CV }

Merci,
Marc
 

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I still don't see the sense of it. I'm not a novice at this either. I have 2 turbo charged cars that I built myself.

The heat in the air comes from the compression from the turbo, just like in an air compressor. At low speed operation, the turbo isn't compressing the air at all, no boost. Once the vehicle is under boost, the air flowing across the intercooler will easily outstrip what a fan can move.

Most that want to cool their intake air use a few different methods, CO2 spray, Alcohol or water spray on the intercooler.
 

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I would not recomend conecting things to the sensors in your vehicle,
You dont know how this could effect the normal operation of the system.
Instead you can have a completly seperate system with its own sensor.
this is much more safer.
And you can configure it to operate at what ever point you like.
 

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Discussion Starter · #11 ·
I still don't see the sense of it. I'm not a novice at this either. I have 2 turbo charged cars that I built myself.

The heat in the air comes from the compression from the turbo, just like in an air compressor. At low speed operation, the turbo isn't compressing the air at all, no boost. Once the vehicle is under boost, the air flowing across the intercooler will easily outstrip what a fan can move.

Most that want to cool their intake air use a few different methods, CO2 spray, Alcohol or water spray on the intercooler.
Yes, supercharged. The idea is that after running hard and then coming to slow speed, the intercooler no longer has the speed of airflow, and it experiences some heat soak. So I guess maybe a speed-triggered fan would be more logical than iat-triggered
 
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