I need to know if I can remove the coolant fan switch from my passenger head and put it inside a spare port i have on my HSR intake? Reason being, the plug and wire to it is way to close to my SLP headers and it is gonna burn AGAIN. Is the coolant a little cooler up there and if so would the engine actually run warmer with it there since the fans wouldnt turn on until that coolant gets up to the turn on temp?

 

oh ya. I ditched my A/C if that matters. I hope fastchip can set up my new prom to have both fans turn on. also, is this sensor even needed? what the difference between this one and the coolant sensor already in the front of the intake

UPDATE: I did a little research on this and here are some questions. First off, as you know my A/C is in the trash. the plug that went to the compressor are gone. they got caught in the belt and.well you now what happens after that. the rest of the plugs are still there. All I want to do is have both my fans work and get the sensor on the passenger head out of there. it is way to close the headers. what can I do to fix this? Is that sensor even needed or what. If need be I will wire up a manual switch but I really dont want to. Id rather have the computer do the work. I also am having fastchip burn me a custom chip this week. Is there anything I can tell them to do to help my cooling issues with this

 

But your SLP headers should have came with a 90* deg. adapter fitting to face your fan switch straight down instead of out. That should have fixed the problem if not call SLP and buy one.
You can also cover the sensor and wire with some heat shielding material as an added security, thats what I did.

Your Ecm controlls the primary fan and the second is controlled by the sensor your talking about.

 

ok thats all fine and dandy if I can buy that fitting from SLP but do I even need that sensor if I dont have A/C anymore.

 

You should have two fan switches in the engine bay. One is a fan, A/C pressure switch located in the A/C pressure line. The other is the heavy duty coolant fan switch which is located in the head above the starter. You have eliminated the A/C so that takes out one fan switch and if you remove the one from the head then you will have no fans unless you run manual switches to them. Just thought!!

 

Too many things to quote, lol.

Trickster, the primary fan would still operate normally because it has nothing to do with the fan switch in the head or the AC pressure switch. Primary is controlled by the ECM and coolant temp sensor in the front of the intake. And no changes there so no worries. He'd still have the primary fan.

And BOTTLEDZr28, unless you plan to ground your secondary fan(either to be hot all the time or to a manual switch), then yes, you need the fan switch that you're asking about because there's nothing else to control the secondary fan since your AC is gone. BUT, you could move it if you wanted to. If you do, to wherever you move it, it will still control only that fan. Or instead of moving it, you could just disconnect it and leave it there as a plug(it's other purpose, lol) and just get a new one for the new location.

If you choose to move it, then you might want a new lower temp fan switch anyway so it'll come on closer to(or at) the on temp of the primary fan/coolant temp sensor/ECM. That way both fans will work together, and you'll get some good use out of the secondary fan, which will likely never come on at the high stock switch temp.

OR..., lol(I know, it's getting long), I recently read someone saying there's a way to splice into the two relays to make both fans controlled by the ECM/coolant temp sensor, but I'm up on that one. That might be the best way for you to go, and just disconnect and leave the fan switch in the head as a plug.

I hope you could follow all that, lol. So in short, yeah, you can move it if you want to. And yeah, you need it.

Edit: Also, moving it would mean it's gotta fit/thread into where you want to put it. It might or might not fit, I dunno.

 

You should be able to just splice the two grounds together at the relay, that way both fans come on at the same time regardless of if its the ECM or the fan switch that grounds it. However, thats a lot of current to run through the ECM and will probably cause it to heat up and shorten the ECM's lifespan. I'd go for the lower temp fan switch and if you get a chip burned, change the fans to come on a couple degrees after the fan switch.

 

ok some good info here BUT.... let me throw this out there, I dont want to splice the two relays. thats a little scary for me. second, I would really like the fans to turn on by themselves when they are suppose to. I dont want a switch in the car. So, I can just get a 160 degree switch and move it to the intake and all is well and my secondary fan will work and come on when the temp reaches 160 degress right? Then I will have my chip setup to have the primary fan come on at say...160 too right? does this sound like a workable setup?

 

Yes, do it, it works great. I do it all the time a when car has that extra port in the intake.

 

thanks. Ill be looking for the temp switch now along with the plug for that spot in the head. This really is a relief to me. That sensor is about 1/4" away from the #6 header tube and I know it will burn once I fire this new engine up for the first time. Do they offer a temp switch at 180 degrees? Or should I just get the 160 one.

 

Check Hypertech and Jet. Between the two of them, you'll find a fan switch with a temp you like(160*, 180* and 200*). As for what temp would be good, that's up to you and what you feel comfortable with for your car.

 

Dunno if his '91 is different than my '88, but in '88, AC most certainly is tied in with the primary fan. If you remove AC it will NOT work correctly, as an open on the AC pressure switch will mean your fan comes on all the time, and the ECM has NO control of it then.

You have to jumper that switch when removing AC.

There is a seperate AC request input into the ECM, again at least in the '88 dual fan setups.

This isn't really what the posters question was, but I'm just clarifying, or attempting to.

For the original poster, I too moved the switch into the intake from the head, but with that switch coming on around 240* or something equally high, I don't expect it to ever be used. I can watch the engine temps drop (either through the ECM or on the gauge) with the one fan on, idling.

Only problem I have is the heater outlet (I put it on the waterpump, wrong thing to do) so I may be going to one of those elbows that was mentioned earlier, and putting the switch back in the stock location. Just so I can run the heater outlet in the stock location.
I will be moving to a switch that comes on around 220* for the secondary fan myself, but since I have no problem running just the one fan normally, that is going to be more of a failsafe than anything else.

 

well I guess I will jut have to find out and see whast happens. I did move the sensor today to the intake of the HSR. The hole was the same pipe thread size so I just switched the fittings. ALl I have to do now is extend the wire. What is this thing you are talking about with the jumper on the A/C connector switch?

 

IF the AC pressure switch is removed. But you don't have to remove that when you remove the AC. I'm sure many do, but I didn't, and I think many others didn't either. So if he didn't, then everything will work just as it's supposed to. And since he didn't say his primary fan was running all the time, which I'd think he'd have mentioned if it was, he either didn't remove the pressure switch, or he hasn't tried the car since removing everything.

BOTTLED, the AC pressure switch is near the coolant recovery tank, plugged into the tube on the frame rail that runs from the condenser to the AC unit. If you didn't pull that, then don't. Just leave it connected.

 

that plug had been unpluge. I took that line right out of the car. The connector is still there though. Can I do something with that connector to make it think the A/C is still there. What would happen with the fan if I turn the A/C on on the HVAC controls?

 

If the switch is gone, and the connector not jumpered, your primary fan should run as soon as you START the engine.

Fan has a 15 second on time requirement IIRC, so don't forget that if you start playing around with jumpers and what not, relating to it.

If you wanted a manual fan switch, you could cut that plug off, and wire in a toggle switch. Depending on how the AC controls are set up, you might be able to use it to "jumper" the two AC pressure switch wires. No real reason to make the engine think the AC is there. If you don't like the on temperature, buy a switch with a lower rated on temp.

The AC pressure switch works by pressure in that line you removed. Over a certain pressure (AC working) the switch OPENS, breaking the path to ground, and the fan turns on. You could just as easily jumper the single wire from the ECM to that switch to ground, but it is cleaner to just cut the connector off, and solder the wires together IMO.

Since I don't have AC, I just cut the connector off, and soldered the wires together. That way the ECM has sole control of the fan. I put in a jumper, temporarily, then forgot about it.

Went on a nice long test drive, got home, fan was on. Started freaking out until I figured out the jumper had fallen out.

Basing all of this off of my '88 setup, so if it is different somehow, someone else will have to chime in.

 

ok so if I cut the connector off and solder the wires togehter then what do yo umean the ECM will have total control of the fan? WHich fan the pass. one right. and what control will is have? all this dilema is just for the second fan right? I shouldnt have to worry about the primary fan at all right? All I want is both fans to come on togheter and shut off togheter, all based on a set temp.

 

Umm, no?

Primary coolant fan is controlled via the ECM, AND by the AC pressure switch. I don't know which fan is primary on your setup, but it SHOULD be running constantly right now.

The secondary fan is controlled ONLY by a temperature switch. (again, all comments regard my '88 setup)

If you remove the AC pressure switch, the primary fan runs constantly. If you JUMPER the AC pressure switch connector, the ECM "assumes", since the switch that is supposed to be there, never switches, that the AC is never turned on. Thus, if the AC isn't on, the ECM temp settings for primary fan operation are all that will control the primary fan. If you don't have AC, jumper that connector or you run the risk of burning out your fan motor. Not only that, it's hard on your charging system.

The way I see it, your option for getting both fans to run at the same time, controlled by the ECM, is to figure out via the wiring, which wire on the primary relay, is the one the ECM grounds when it commands the primary fan on. Once you figure out which wire that is, you would cut the one that right now goes to your secondary fan switch (the one in the head) and splice that into the ECM wire that is grounded to command the fan on.

It's pretty simple to tell really. On the primary fan relay, there are 4 wires. Two large, two small. The two small ones are the ones you are concerned with. One small one should have voltage to it with key on, engine off. The other wire is the ECM wire.

If you do it how I suggest, both relays will stay in use, but both will come on when the ECM commands fan1.

I'm not going to say this is SAFE, or a good idea, only that it is how you would go about it. It very well could be that using the same small wire to ground both circuits is a bad idea, but I'm not enough of an electrical expert (actually not an expert anyways) to say yes it is ok. I'd hate for you to think you will have no problems doing this, when in fact it is entirely possible.

Going way back, instead of all this hassle, why not get a 90* like was suggested way back in this thread? I didn't even think of this as an option before, I may go this route now.

 

ok here is what I am gonna do. Im gonna have the primary fan turn on at 185 and off at 200 via the prom I am having burnt for me. The seconadary fan will use the sensor but I will put it in the intake and use the stock sensor for now and see what happens. If the engine starts running a little too hot then I will get the lower fan switch and go from there.

 

Sounds like a plan.

Watching my engine with a scanner, I'm going to have my fan turn on a bit sooner, but not too much...as it is now it turns on right about 220*, and off right around 195*. (195 t-stat) Doesn't leave much of a margin on the gauge if temperature gets to 220*, then starts to skyrocket. That could happen in two seconds and you'd never see it.

I'm really impressed with the LT/LS fans...one of them is enough to cool my engine from the above, at idle, in about 2 minutes. Temp drops very quickly, enough that I can actually see the needle move.

Of course, my radiator is probably large by huge compared to the car one (19" tall 3 core) and has a much better grille opening, for cooling anyways. In any case, radiator condition should never be overlooked or assumed to be good, if you think you are having cooling issues.

 

https://www.thirdgen.org/techbb2/sho...ht=fan+control

https://www.thirdgen.org/techbb2/sho...cm+fan+control

this should help

 

I have both of my fan relays triggered by the ECM. The Coolant Fan Switch on the Passenger side is wired in parallel with the ECM, if the ECM fails to ground the relays the Coolant Fan Switch will turn them on at it's temperature set point.

 

I never got a 90* elbow from SLP with my headers. Anyone have a picture of this little sucker?

 

I moved it to the intake with NO problems. Works fine.

 

About this subject. When I rebuilt my engine (over the last month), I put on the 113 heads from a 90 vette. It has a recess, but no hole for the Coolant Temp Sensor in the passenger side head. Am I screwed?

 

If your using an aftermarket base with an 89 and newer, you could use the Cold Start Injector sensor hole on the front of the intake.

 

Well, yes, except I have that one already plugged up to the other connector. By the way, my Formula is an 88, and the intake is a 90. The wiring harness had two original locations, so, I still have this one dangling. I'll keep searching.