AC fan

[mattspyder]

How can i wire up my ac fan to turn on with a flip of a switch,
i read the VFAQ article how wiring both of them up to come on,
but like i said i just want the ac fan to come on, would i just wire it up using the AC fan relay.

 

[steve]

Hook the switch up to ground that fan relay's coil just like the ECU does to turn the fan on.
That VFAQ is braindead. You don't want to switch the power circuit for the fans you want to switch the control circuit. You can even do it without pulling wire outside the interior. Just tap the ECU's wires for the fan relays.

Steve

 

[mattspyder]

wow sounds to complicated to me?? i dont get it

 

[steve]

The relays aready switch power to the fans (the power circuit). The ECU controls the relays by pulling one side of the relay coil to ground to switch them on (the control circuit).

On the 2G turbo and spyder the ECU uses pin 20 to turn on the high speed for the radiator and condensor fans and pin 21 to turn on the low speed of the radiator. If you ground pin 20 via a switch you'll override the ECU and turn those fans on high whenever the switch and ignition is on. The low speed of the condensor fan is controlled by the AC computer.

This way your only switching a couple hundred milliamps (the current through the relay coil) rather than tens of amps to power the fans.

Steve

 

[mattspyder]

ok im starting to understand it! so i just tap into pin 20, whatever wire that is going into the ecu, run the wire up to the switch, ground the switch, and of course connect it to a power supply!
This will turn Both fans on or just the AC fan?
also if it does turn both fans on, will my passenger side fan still work when the switch is off??

 

[steve]

tap into the wire going to ecu pin 20, run the wire up to the switch, ground the switch, and of course connect it to a power supply!
This will turn both fans on or just the AC fan, if it does turn both fans on, will my passenger side fan still work when the switch is off??

No connection to any power supply is required (connecting one will blow up your ECU). The two fan relay coils will have power to them anytime the ignition switch in in run or start, your just creating another way for that voltage to reach ground and make current flow.

According to the 2G wiring diagrams that will make both the fans run on high. If you want control over just the AC fan then you will have to get a little more involved.

With the switch off everything works like normal.


Steve

 

[mattspyder]

what about this
http://vfaq.com/mods/wayback/2gcoolingfan.html

this makes more sense to me... its all about getting in the fuse under the hood!!!

 

[steve]

this makes more sense to me.

Why does that make more sense to you? Because of the presentation?

That is exactly what I was talking about before. The way the switch is used causes it to carry all the current for the fans, which is really unnecessary and can be unsafe. Also note the caution at the bottom. The way this mod is done the fans will run with the switch on even with the car off.

Steve