Question for those that have swapped out their radiator fan for an AC one

[GRSHOPR]

OK, so my passenger radiator fan went out, and since I'm planning on using larger turbos in the future, I decided to do what had been advised by others, and swap it out with the slimmer A/C fan, and hotwire them. Did the hotwire, installed the fan, but when I plug it in, it turns on, with or without the key in the ignition. The driver side one works properly, only when the key is to the ON position, but what's up with the passenger side one?? Anyone who has done this mod before got an answer?? Did I miss something? Thanks.

[mb3000]

My guess is that you wired straight to the battery, therefore it will run all the time. You need to connect it to a wire that only gets juice when the key is in the ON position, or while the engine is running at least.

[BaadVR4]

OK, so my passenger radiator fan went out, and since I'm planning on using larger turbos in the future, I decided to do what had been advised by others, and swap it out with the slimmer A/C fan, and hotwire them. Did the hotwire, installed the fan, but when I plug it in, it turns on, with or without the key in the ignition. The driver side one works properly, only when the key is to the ON position, but what's up with the passenger side one?? Anyone who has done this mod before got an answer?? Did I miss something? Thanks.

In the stock configuration, the passenger side fan is "switched" on the ground side while the driver's side is done on the power side. What you need to do is wire a relay into the passenger side wiring. Run an additional fan "ground" side through the relay. Wire the relay operating lugs with the power to close the relay coming from the power side of the driver's fan. That way, the passenger fan will operate just like stock from the temperature sensor, but will also come on anytime you turn the AC on. This way you get the best of both set ups and both fans will run anytime the AC is operating. Really helps with AC when the car is moving less than 35 MPH and you have a big FMIC.

[GRSHOPR]

In the stock configuration, the passenger side fan is "switched" on the ground side while the driver's side is done on the power side. What you need to do is wire a relay into the passenger side wiring. Run an additional fan "ground" side through the relay. Wire the relay operating lugs with the power to close the relay coming from the power side of the driver's fan. That way, the passenger fan will operate just like stock from the temperature sensor, but will also come on anytime you turn the AC on. This way you get the best of both set ups and both fans will run anytime the AC is operating. Really helps with AC when the car is moving less than 35 MPH and you have a big FMIC.

And what if it's hotwired to run all the time?? Just do the relay?? Would that change the wiring configuration?

[GTOJOE]

In the stock configuration, the passenger side fan is "switched" on the ground side while the driver's side is done on the power side. What you need to do is wire a relay into the passenger side wiring. Run an additional fan "ground" side through the relay. Wire the relay operating lugs with the power to close the relay coming from the power side of the driver's fan. That way, the passenger fan will operate just like stock from the temperature sensor, but will also come on anytime you turn the AC on. This way you get the best of both set ups and both fans will run anytime the AC is operating. Really helps with AC when the car is moving less than 35 MPH and you have a big FMIC.

This is correct. Same as what I advised you on the other thread. Hotwired or not the same rules apply. You need another relay.

[BaadVR4]

And what if it's hotwired to run all the time?? Just do the relay?? Would that change the wiring configuration?

When you say "hotwired to run all the time", just how did you do that? The stock wiring has 12V to the passenger side fan without a switch. Just like a wire directly from the battery to the fan. The fan is then turned on and off by a relay that opens and closes the ground wire. The driver's side fan is done the other way around; the relay that turns it on opens and closes the 12V supply. So, if you connect the wiring from both fans together, they would both run constantly, even with the key removed. I, personally, would not run the fans "full time". With the relay set up I described, the fans will be controlled just like Mitsu designed them except when the AC is on and then both fans will run all the time. I have the typical "big" FMIC and Koyo radiator on two cars. Both are 16G turbo set ups and the AC on both work about the same. When it's really hot and humid (triple digits on both) here in middle Georgia, they will hold 25-30 degrees colder than ambient idling at a standstill. I have a dead stock VR4 and it only does about 5-10 degrees better. Now, my wife's 05 Ford Ranger puts out 44 degree air, no matter how hot it gets outside. Of course, it doesn't make 600+ AWHP, either.

Let me know how you did the "hotwire" and I can better tell you what I'd do. LMK. Thanks.

[GTOJOE]

I believe he has had them wired up to run constantly.

[GRSHOPR]

Lol, yeah, I know, Joe. I was just seeing if there was an easier way. I did the standard splicing together on the A/C relay (green with black chaser and black wire). I have a spare relay spot in the under hood fuse box. Think the standard Mitsu relay would be able to hold the power needed to run the fan?? I'll just run the constant power through the relay, and tie the ignition circuit into the activation circuit.

[BaadVR4]

Lol, yeah, I know, Joe. I was just seeing if there was an easier way. I did the standard splicing together on the A/C relay (green with black chaser and black wire). I have a spare relay spot in the under hood fuse box. Think the standard Mitsu relay would be able to hold the power needed to run the fan?? I'll just run the constant power through the relay, and tie the ignition circuit into the activation circuit.

That should work. I standard 30 amp relay (like the one used for fuel pumps) should be just finel

[GRSHOPR]

Hahahaha, or, since they are virtually useless now, what if I rewired one of the High/Low fan relays for the job?

[BaadVR4]

As long as the power to the driver's fan "closes" the relay which then closes the ground side of the passenger fan, that will do just fine.

[GRSHOPR]

What's a good place to tap into the ignition circuit for this one??

[GTOJOE]

What's a good place to tap into the ignition circuit for this one??

I would be using the existing circuit as it will close the circuit already when the ignition turns on. You just need to use the original negative line as the trigger and have it switch the constant power on.

[GRSHOPR]

Not sure what you mean.

[GTOJOE]

Going to the fan there is a constant 12 volt +pos power which needs a switch [read relay] added in line and there is a negative power/earth. In our cars the switch connected to the ignition is actually switching the -neg not the +pos but we need to switch the +pos instead. The relay for this neg switching should be in the main relay fuse box under the bonnet/hood. If you can locate this and use the same ignition source that powers this relay to power your new relay.

[GTOJOE]

Alternatively you could locate this relay and rewire it. As it is currently setup it has ignition power to power the coil and switch the neg to the fan. If you cut the neg wire at the fan and earth it directly to the body and use the original relay to switch the +pos instead of the -neg. This would be much neater. I just don;t know where the relay is.....sorry.

[GRSHOPR]

So basically, I could run the negative ignition switch wire, after the relay, to the positive feed in the fan relay?

[GTOJOE]

basically the way it is currently setup there is a constant +pos power which needs to be cut and the relay put in between the 2 ends to act as a switch. You then need a power source/trigger to power the coil in the relay to turn the switch on when the ignition is on. So I suggest you find another relay in the system that also turns on when the ignition is on and just jump the wires off it to power the new relay. Or try to somehow use the existing relay and rewire it.

[GRSHOPR]

That's exactly what I was thinking. But I was curious as to where I could tap into an ignition source.

[GTOJOE]

just check any of them. The draw from a relay coil is bugger all so don't need to worry too much current draw. I would suggest the best on though would be the origional relay. Just leave it as is and use the ign trigger for the new relay as well.

[Hans@GZP]

I keep it simple and wire it into the stock passenger side plug. Just cut off the plug from the original passenger side fan so you have a plug in fan just like stock. For a 2nd gen, the blue wires from the slim fan would wire to the red wire on the body side of the plug. The black wire would go to the blue w/green stripe wire on the body side of the plug. Then the 2 wires that would correspond to the black wire and blue w/yellow stripe wire on the body harness would get spliced together. They are for the resistor, so you are basically bypassing the resistor and going straight to ground. This way will make the fan turn on with the stock temp sensor and it will work just like it did from the factory with the only exception being that there will be no low speed fan, only high.

It should be virtually the same for a 1st gen as well. I'm not sure if the colors of the wires are the same though.