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bokey
06-12-2007, 02:46 PM
do cooling fans usually pull? I have a dual fan setup right now. The fans them self are about 10-12'' in diameter.


edit:

was poking around; found that 11-12 amps seems to be average?

BonzoHansen
06-12-2007, 05:11 PM
On start up then can momentarily spike over 20. On running it is less. Why?

bokey
06-13-2007, 11:24 AM
The PO set up the cooling fans (two fans) incorrectly. He has the hot wired into the IGN wire so the fans are running all the time (and putting unnecessary strain on the electrical system). I can tell that when both fans are running that the system drops a few volts. For the time being, I disconnected one of the fans.

I wanted to know, is there a guide or something where it outlines the CORRECT way to wire in an electric fan? Right now there is no temp sensor on that i know of so I wouldn't be able to go that route.

Thanks for any help in advance

bubba428
06-13-2007, 11:37 AM
I think the Hanes manual does

BonzoHansen
06-13-2007, 11:37 AM
You need relays and such. Search this forum, there are a number of threads on it.

bokey
06-13-2007, 11:56 AM
didn't find anything -- going to take a gander over at tgo

BonzoHansen
06-13-2007, 12:45 PM
http://www.njfboa.org/forums/showthread.php?t=17042
http://www.njfboa.org/forums/showthread.php?t=17304
http://www.njfboa.org/forums/showthread.php?t=17456
http://www.njfboa.org/forums/showthread.php?t=18685
http://www.njfboa.org/forums/showthread.php?t=24790
http://www.njfboa.org/forums/showthread.php?t=25454

bokey
06-13-2007, 03:03 PM
Guess I typed in the wrong thing into the search? ...but still really hasn't helped me much. I'll need a CTS, but I dunno where I would put one? There looks to be a screw into of my water pump; possibly where a sensor would screw in? I suppose from there, I could hook that up to a relay?

For right now, the best mode of operation seems to be make a ground switch for the fans. This way I do not have to worry about amp ratings on the switch, and (as far as i know/heard) it is better to run a ground switch then a hot switch. Is it suggested that I fuse the fans as well?

BonzoHansen
06-13-2007, 04:51 PM
If this one doesn't help you, not sure what will:
http://www.njfboa.org/forums/showthread.php?t=17456

Fan switch (not to be confused with coolant temerture sensor) locations that work: side of RH head or t-stat housing.

A manual swtich is not a good setup as it requires your constant attention. And you'd still need a relay to use one. Just because you are on the ground side does not mean you can use low amp stuff, unless you mean for the trigger circuit and not the fan power circuit.

What kind of car is this (year/engine)? Are they factory fans?

bokey
06-14-2007, 08:31 AM
you most certainly do not need a relay to have just one fan to work. Right now, I just have the one disconnected (two prong plug).

And for right now, until I get a temp sensor and relay in, I am just going to throw a switch in. I'm not sure if there really is a problem with such a setup (unless you are forgetful, etc.) Every time I do get into the car I switch the fan on and go. I never had a problem in the past with forgetting this (had a switch put into my camaro a few years ago). This isn't, by any means a permanent solution, but for now it will get the job done.

The car is a '87 GTA, Carb'd 350. As far as I know the fans are the stock ones.

And again, thanks for your help so far! :)

BonzoHansen
06-14-2007, 09:04 AM
you most certainly do not need a relay to have just one fan to work. Right now, I just have the one disconnected (two prong plug).

And for right now, until I get a temp sensor and relay in, I am just going to throw a switch in. I'm not sure if there really is a problem with such a setup (unless you are forgetful, etc.) Every time I do get into the car I switch the fan on and go. I never had a problem in the past with forgetting this (had a switch put into my camaro a few years ago). This isn't, by any means a permanent solution, but for now it will get the job done.

The car is a '87 GTA, Carb'd 350. As far as I know the fans are the stock ones.

And again, thanks for your help so far! :)I thought you wanted to do it right. :scratch:

If you use no relay, the switch is part of the circuit and needs to handle the amperage-it is all part of the circuit. You'll need pretty big wire too (8g), to make up for the increased length and the associated volatage drop.

Why wouldn't you want to use a $5 relay? If you use one, you can run about 4' of heavy wire (10g or 12g), and run small wire to your switch.

WildBillyT
06-14-2007, 09:29 AM
I thought you wanted to do it right. :scratch:

If you use no relay, the switch is part of the circuit and needs to handle the amperage-it is all part of the circuit. You'll need pretty big wire too (8g), to make up for the increased length and the associated volatage drop.

Why wouldn't you want to use a $5 relay? If you use one, you can run about 4' of heavy wire (10g or 12g), and run small wire to your switch.

I agree. Use a switch, a relay, and 10g wire. I set up dual Taurus fans this way and they work great.

bokey
06-14-2007, 10:00 AM
I agree. Use a switch, a relay, and 10g wire. I set up dual Taurus fans this way and they work great.

Yeah you are both right ... if I am going to do it, do it once, and do it the right way.

Do you have a sketch/picture of how yours is set up?

BonzoHansen
06-14-2007, 10:21 AM
1 fan?

bokey
06-14-2007, 10:48 AM
I have two fans. I have never done anything with a relay before, so sorry in advanced for any silly quesitons

WildBillyT
06-14-2007, 11:32 AM
I have two fans. I have never done anything with a relay before, so sorry in advanced for any silly quesitons

It's really simple. Conceptually, the switch will control the actuation of the relay, which controls the current.

The relay will have a ground, a hot lead, a lead to the fans, and a lead to the switch. The terminals on the relay are marked so you know where to connect things.

Post up whatever questions you have! :D

V
06-14-2007, 12:04 PM
wire the relay up properly, using a harness for the dual fans, not that hard to find. It has the two relays in it, one comes on at the specified temp and the other comes on as well if the a/c is turned on. The relays/wiring should be intact in the GTA to begin with, just a matter of maybe repairing some wires.

do NOT run a fan on just a switch, especially to the ignition terminal on the fuse block. Not only WILL you overheat and melt the switch, but in many cases, when you turn off the car, it can "diesel" as if its still trying to run. That is caused by the fan going from an electric motor, to basically what you could call a generator. It will then create a small amoutn of voltage and feed it back into the fuse block. Ive seen that in several cases. You asked how to do it right...and thats with one relay PER fan.

BonzoHansen
06-14-2007, 12:48 PM
You can get fancy and use 3 relays and 2 fan switches for 2 fans. :)

bokey
06-14-2007, 01:15 PM
would this be a good start?

edit: also -- what kind of relay would I use? Did a search, and there seems to be a plethora of different types of relays :?

WildBillyT
06-14-2007, 01:26 PM
would this be a good start?

edit: also -- what kind of relay would I use? Did a search, and there seems to be a plethora of different types of relays :?

I used a Bosch 30A, $9.95 at Summit.

BonzoHansen
06-14-2007, 01:57 PM
I'll draw you a pic later. They have relays at radio shack and advance auto, napa, etc...

V
06-14-2007, 02:27 PM
would this be a good start?


that schematic is a mess, not even functional.


do it similar to this...
1st is with relay on groudn side
2nd is with relay on positive side
both will work

WildBillyT
06-14-2007, 02:37 PM
that schematic is a mess, not even functional.


do it similar to this...

Paul, you ground the fan to the relay? I wired in a way similar to the first schematic and it worked fine...

V
06-14-2007, 02:40 PM
Paul, you ground the fan to the relay? I wired in a way similar to the first schematic and it worked fine...

it will work both ways, on some circuits in cars the ground connection is relayed. i added a diagram how to wire it the other way around too.

In bokeys schematic, the connection to the right of the switch must be a + source, not ground for it to work, OR both connections to the left of the relay must be +


heres one with the switch to a ground....

WildBillyT
06-14-2007, 02:43 PM
it will work both ways, on some circuits in cars the ground connection is relayed. i added a diagram how to wire it the other way around too.

In bokeys schematic, the connection to the right of the switch must be a + source, not ground for it to work, OR both connections to the left of the relay must be +

Yeah, the second way is how I did it. :nod:

BonzoHansen
06-14-2007, 02:43 PM
Relay looks like this:
http://www.madelectrical.com/images/relayk5.jpg

Buy a kit like this ( http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRF%2D30103&N=700+115&autoview=sku) from Summit. Then you get a switch, a relay, some wire, a breaker & a relay. Get another relay locally, and you will be well on your way.
http://store.summitracing.com/largeimage.asp?part=PRF-30103&Prod=Painless+Performance+FAN%2DTHOM+Electric+Fan+ Relay+Kits&img=prf-30102.jpg

You may be able to cobble it together cheaper, but not much.

Wiring Diagram
http://img523.imageshack.us/img523/3433/fandiagram2sy0.th.jpg (http://img523.imageshack.us/my.php?image=fandiagram2sy0.jpg)


*purple wire needs to be fused at source
*I might use breakers instead of links for the main power - not fuses though.

V
06-14-2007, 02:47 PM
billy, yeah, there are many ways to possibly wire it. and like in the diagram bonzo showed the grounds go to a temp switch which i didnt even include in my schematics.

BonzoHansen
06-14-2007, 02:49 PM
I like grounding the temp switch. That is what GM does.

BonzoHansen
06-14-2007, 02:51 PM
If I was using fan switches, I'd do this, replacing the ECM leads for fan switches (one in head, the other in the water neck or something).
http://img.photobucket.com/albums/v359/SIBLY/Cars/th_fan_schematic_1995_BOTTOM.jpg (http://img.photobucket.com/albums/v359/SIBLY/Cars/fan_schematic_1995_BOTTOM.jpg)

I'm loving my DCC controller, though.

V
06-14-2007, 02:51 PM
I like grounding the temp switch. That is what GM does.

yeah thats a good idea. i just completely forgot about them lol

BonzoHansen
06-14-2007, 02:52 PM
yeah thats a good idea. i just completely forgot about them lol

Makes rigging a manual switch easier too - no extra fuse.

bokey
06-15-2007, 03:58 PM
okay -- that works, thanks for that diag.

So all I need to get now is some 10g wire and a relay. Again, as I said before, not sure what kind of relay to get. Went to the radio shack website, and came up with this:
http://www.radioshack.com/search/index.jsp?kwCatId=&kw=relay&origkw=relay&sr=1

Which one do I choose?

V
06-15-2007, 05:42 PM
i suggest this one... for high curent...
http://www.radioshack.com/product/index.jsp?productId=2501525&cp=&pg=1&sr=1&origkw=relay&kw=relay&parentPage=search

bokey
06-19-2007, 10:46 AM
I thought you wanted to do it right. :scratch:

If you use no relay, the switch is part of the circuit and needs to handle the amperage-it is all part of the circuit. You'll need pretty big wire too (8g), to make up for the increased length and the associated volatage drop.

Why wouldn't you want to use a $5 relay? If you use one, you can run about 4' of heavy wire (10g or 12g), and run small wire to your switch.

After talking to several mechanics (one of which is an 20+ year mechanic) my original though of just using a switch and no relay is correct.

A relay is a switch ... unless there is a sensor (or something else) that dictated when the fan turns on or not there is no need for one. Why would one hook up a switch just to turn another on another switch?

You don't need 8g wire... not even close (maybe if i'm going to wire something in a house with a 120v). I am running 12 g wire to a 30A switch and have not had a single problem. The switch DOES NOT get hot, neither do the wires.

V
06-19-2007, 11:05 AM
i still recommend a switch.. but its your car.
and i also doubt those mechanics went to Stevens Tech for electrical engineering..

I will say, in the car hobby, everyone has different opinions and thats fine, most of it is trial and error or past experiences. ive seen issues a lot with high amp switched circuits so that formed my veiws. If someone never saw an issue, they woudlnt have a reason to question it. Just always keep and eye on the switch you are using and the connections, if you see any browning of the terminal connectors, change it asap.

BonzoHansen
06-19-2007, 12:04 PM
Yup, local wrench is smarter then the OEs. And we just fell off turnip trucks.

Good luck.

bokey
06-19-2007, 02:12 PM
Yup, local wrench is smarter then the OEs. And we just fell off turnip trucks.

Good luck.

never said that... but assume away

What I am saying is that I would take my best friend's evaluation (A tech at Ford) and my pops evaluation (20+ year professional mechanic at Ford). He also took many courses in electrical engineering.

Smoking SS:

Been keeping an eye on the switch and the wires and never once have they got hot. Had the fan on for an hour and a half straight the other day and no issue.

WildBillyT
06-19-2007, 03:01 PM
never said that... but assume away

What I am saying is that I would take my best friend's evaluation (A tech at Ford) and my pops evaluation (20+ year professional mechanic at Ford). He also took many courses in electrical engineering.

Smoking SS:

Been keeping an eye on the switch and the wires and never once have they got hot. Had the fan on for an hour and a half straight the other day and no issue.

bokey- Their skills as automotive specialists are not in question here.

But to value their ideas over that of teams of electrical engineers that design these circuits may be a bit of a mistake.

It's not just the fact that the relay is switched, it's also that the relay prevents against voltage drop. Don't believe me? :mrgreen: Take a look at "headlight upgrade kits" for old muscle. They are all wiring upgrades that include a relay.


http://www.madelectrical.com/electricaltech/brighter-headlights.shtml

Now this is a worst case scenario but it kind of shows what I mean...