How many amps...
 

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?

On start up then can momentarily spike over 20. On running it is less. Why?

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

I think the Hanes manual does

You need relays and such. Search this forum, there are a number of threads on it.

didn't find anything -- going to take a gander over at tgo

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

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?

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?

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.

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?

1 fan?

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

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.

You can get fancy and use 3 relays and 2 fan switches for 2 fans. :)

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.

I'll draw you a pic later. They have relays at radio shack and advance auto, napa, etc...

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

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....

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