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Guest Message by DevFuse
 

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another way to wire your electric A/C fan


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7 replies to this topic

#1 Marck

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Posted 28 May 2004 - 01:21 AM

Ok, after reading this post: http://www.ultimates...light=gauge fan
and other fan wiring threads over and over again, I think I figured out how I want to wire my electric radiator fan. People with 1987 FSMs please look at page 69 of section 4-7. There you will see the wiring diagram for the A/C for the 1987 EA82(T) cars (I think this will apply to all other years of EA82(T) with A/C, but I am not sure). Now study the section of the diagram with the radiator fan motor, thermoswitch, radiator fan relay, and Pressure (main fan control) switch. My plan is to is to place a switch between the LR and LW wires on the Pressure (main fan control) switch (F18). Doing it this way will short that switch which is used to turn the fan on through a relay when the A/C is on. This method will take use of the factory Radiator Fan Relay (that is sitting behind the passenger side strut tower) to turn on the fan. So I have the safety and durability of using a relay without having to go through the trouble of rewiring the whole deal and buying a relay. Will this work? Do you see any problems with this method?

This will allow you to turn on the radiator fan manually with the switch, allow the fan to still turn on when the A/C is on, and it will turn on fan (using the thermoswitch in the radiator) when the engine is running too hot (don't rely on that :rolleyes: ).

I am going to hunt for the 'Pressure (main fan control) Switch' tomorrow. I have a pretty good idea of where it is at from looking at pages 7-11 in section 6-3. It is connector F18. The only way I know how to identify it is by the colors of the wires that are coming out of it.

It has a LB colored wire, a RW colored wire, LR colored wire, and a LW colored wire. Remember, we want to short (or place a switch between) the LR and LW colored wires to make the fan turn on.

LB = Blue with Black stripe
RW = Red with White stripe
LR = Blue with Red Stripe
LW = Blue with White Stripe

UPDATE: Now that I think of it, the same effect is achieved by shorting the LW colored wire at the Radiator Fan Relay and the LR colored wire coming from the fan. That way, I don't have to hunt for the 'Pressure (main fan control) Switch'. (I am learning a lot :banana: )

I can scan the A/C wiring diagram that I am refering to, but I am not able to post it on USMB. So if some one wants to help me out by posting the diagram for me then let me know and I can then send you the scanned image of the diagram via email.

#2 MilesFox

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Posted 28 May 2004 - 01:55 AM

find the thermoswitch on the radiator, then the blue clip it plugs into. those are the wires you wnt to short, or anywhere else in the schematic for the same wires. this is what we did to the rx, using speaker wire to a toggle in the car.

on the trashwagon, i made a temporary fix bt jumping a wore from the yellow wire to the body, to gound out the fan and turn it on. and this way the fan goes off with the key.

you may have read the arguement but what my example was is the same thing you are asking about.

#3 Marck

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Posted 28 May 2004 - 02:00 AM

MilesFox : Those aren't the wires I am talking about. The way I am doing it uses the Fan relay. The thermosensor doesn't use the relay, but the AC Pressure switch does. That is the difference.

#4 MilesFox

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Posted 28 May 2004 - 02:04 AM

oops my bad. maybe i should have responded to the other post instead!

#5 Marck

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Posted 28 May 2004 - 03:11 PM

Okay, I shorted the LW colored wire at the Radiator Fan Relay and the LR colored wire coming from the fan and it works :banana: . This is a good way to test your main fan relay. Now instead of shorting these two wires, I will place a switch in between them and mount the switch somewhere in the dash.

To minimize the amount of wire used do this:
I also noticed that the LR colored wire that goes to the fan comes from the 15 Amp Fuse (Fuse #15) in the Fuse Box in the dash. So you can splice in there. And then run another wire from the LW colored wire coming from the Radiator Fan Relay. Hook those two wires to a switch and your set.

I also found the 'Pressure (main fan control) Switch', although you don't need to know where it is to wire this up. The 'Pressure (main fan control) Switch' is attached to the side of the Receiver Drier (canister thing with the sight glass).

Do I get the seal of approval? I can't believe no one else thought of this. Why buy a relay and wire it up when Subaru already gave you one to work with.

#6 beachbum

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Posted 28 May 2004 - 06:00 PM

hey marck,just a thought but with both fans running thru 1 relay regardless of a switch, wont that shorten the life of the relay? reason why soob put in 2 to begin with? dont want to burst ur bubble and it sounds great i hope it works,cause if it does i might even do that:brow: ,but like i said to begin with jusy a thought. gluck

#7 Marck

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Posted 28 May 2004 - 06:22 PM

I am only wiring one fan and keeping the mechanical fan installed. Not sure what I would do if I wanted to wire up a second. I think I would just wire it in parallel with the other fan. I don't know if that would shorten the life of the relay?

reason why soob put in 2 to begin with?


Subaru didn't put in two relays for the fan. The one with the black connector is for the A/C and the one with the brown connector is for the radiator fan.

#8 beachbum

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Posted 28 May 2004 - 06:24 PM

like i said just a thought im glad it works and hope it stays working later:)




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